Search Results

Search found 13099 results on 524 pages for 'front row'.

Page 159/524 | < Previous Page | 155 156 157 158 159 160 161 162 163 164 165 166  | Next Page >

  • How to Save Hundreds or Thousands of Dollars on Cell Phone Service

    - by Chris Hoffman
    Cell phone contracts are bad. You get a seemingly cheap phone up front, but you more than pay for the cost of the phone over two years. Prepaid phone plans are surging in North America for a reason. Prepaid phone plans will be cheaper and more flexible than traditional contracts with big carriers for many people. However much you use your phone, there’s a good chance you can save money with a prepaid service. No More Contracts Here’s how cell phone service typically works in North America: You get a subsidized phone for “free”, $99, or $199. You sign up for a two-year contract and more than pay back the cost of that phone over the length of the contract. This is similar to leasing something or purchasing it on a credit card and paying it back over two years — you spend less up front, but you’re paying more in the long run. But this isn’t the only option. You could opt for a cheaper prepaid service that doesn’t lock you into a contract. If you don’t use your phone much, you could just pay for what you use and avoid the hefty cell phone bills. If you use your phone a lot, you could get a cheaper plan, too. Now, this certainly isn’t for everyone. If you want the latest iPhone or Galaxy smartphone every two years and require a 4G data connection, prepaid services may not be for you. On the other hand, if you don’t need the latest phone, you can save money here. You can also save a huge amount of money if you don’t use your phone much. Phone Options When you choose your prepaid or contract-free service, you’ll often be able to purchase a phone from them. You’ll generally be able to find dirt-cheap dumbphones and the cheapest, slowest Android phones for not very much money. If you are able to buy a top-of-the-line smartphone, you’ll have to pay the full, unsubsidized price. That’s $649 for either an iPhone 5S or Samsung Galaxy S4. Whatever phones the service provider offers, you could always buy a phone elsewhere — for example, you could buy an unsubsidized iPhone direct from Apple and then take it to your cell phone service of choice. Most services will allow you to get a SIM card and pop it into your existing phone rather than purchasing a phone. If you can get a hand-me-down smartphone, you can often save quite a bit of money. For example, you may have a family member upgrading from an iPhone 4S to an iPhone 5S. You could take their phone to a prepaid carrier and have a nicer phone on a cheap cell phone plan. If you brought an old smartphone to a big carrier like AT&T or Verizon, they wouldn’t give you a discount on your monthly plan. You’d have to pay the same amount of money every month as if you had gotten a subsidized phone. Google’s Nexus phones are also great options for people looking to buy smartphones and pay up-front. Google’s Nexus 4 offered a modern, almost top-of-the-line Android smartphone experience at $299 or $349 when it came out last year. Google will soon be releasing the Nexus 5 and it’s expected to be priced at $349. That’s certainly a lot more than a cheap phone, but it’s a fairly high-end smartphone at almost half the price of an iPhone 5S or Galaxy S4. Nexus phones can be purchased online from Google’s Play Store. Service Options When choosing a service, you need to consider what you actually use. If you’re someone who only uses your phone rarely, you can get plans that will allow you to pay as little as a few dollars per month. If you’re someone who’s usually in range of Wi-Fi, you may not need much data at all. If you want a plan with unlimited talk, texting, and data usage, you can get it for much cheaper than you’d pay on a major carrier like AT&T. The options here range from pay-as-you-go plans, like the ones offered by T-Mobile, which allow you to put a certain amount of money in and only drain that balance when you actually use minutes, texts, or data. If you only make a few calls and send a few texts per month, you’d only pay a few bucks. On the other end, Walmart’s Straight Talk service is a popular option that offers unlimited talk, texting, and data at $45 per month. Which service is right for you depends on a lot of things, including your usage and what each network’s coverage is like in your area. You’ll want to do some research of your own before choosing a service. Prepaid services also offer you even more flexibility after you choose one. If you’re not happy or a better deal comes along, you can switch — you’re not locked into your service for two years and you won’t pay an early termination fee. Image Credit: Intel Free Press on Flickr, Jon Fingas on Flickr, John Karakatsanis on Flickr, kendalkinggroup on Flickr     

    Read the article

  • NOOB Memory Problem - EXC_BAD_ACCESS

    - by Michael Bordelon
    I have been banging my head against the wall for a couple days and need some help. I have a feeling that I am doing something really silly here, but I cannot find the issue. This is the controller for a table view. I put the SQL in line to simplify it as part of the troubleshooting of this error. Normally, it would be in an accessor method in a model class. It gets through the SQL read just fine. Finds the two objects, loads them into the todaysWorkout array and then builds the cells for the table view. The table view actually comes up on the scree and then it throws the EXC_BAD_ACCESS. I ran instruments and it shows the following: 0 CFString Malloc 1 00:03.765 0x3946470 176 Foundation -[NSPlaceholderString initWithFormat:locale:arguments:] 1 CFString Autorelease 00:03.765 0x3946470 0 Foundation NSRecordAllocationEvent 2 CFString CFRelease 0 00:03.767 0x3946470 0 Bring It -[WorkoutViewController viewDidLoad] 3 CFString Zombie -1 00:03.917 0x3946470 0 Foundation NSPopAutoreleasePool Here is the source code for the controller. I left it all in there just in case there is something extraneous causing the problem. I sincerely appreciate any help I can get: #import "WorkoutViewController.h" #import "MoveListViewController.h" #import "Profile.h" static sqlite3 *database = nil; @implementation WorkoutViewController @synthesize todaysWorkouts; @synthesize woNoteCell; @synthesize bi; //@synthesize woSwitchCell; - (void)viewDidLoad { [super viewDidLoad]; bi = [[BIUtility alloc] init]; todaysWorkouts = [[NSMutableArray alloc] init]; NSString *query; sqlite3_stmt *statement; //open the database if (sqlite3_open([[BIUtility getDBPath] UTF8String], &database) != SQLITE_OK) { sqlite3_close(database); NSAssert(0, @"Failed to opendatabase"); } query = [NSString stringWithFormat:@"SELECT IWORKOUT.WOINSTANCEID, IWORKOUT.WORKOUTID, CWORKOUTS.WORKOUTNAME FROM CWORKOUTS JOIN IWORKOUT ON IWORKOUT.WORKOUTID = CWORKOUTS.WORKOUTID AND DATE = '%@'", [BIUtility todayDateString]]; if (sqlite3_prepare_v2(database, [query UTF8String], -1, &statement, nil) == SQLITE_OK) { while (sqlite3_step(statement) == SQLITE_ROW) { Workout *wo = [[Workout alloc] init]; wo.woInstanceID = sqlite3_column_int(statement, 0); wo.workoutID = sqlite3_column_int(statement, 1); wo.workoutName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, 2)]; [todaysWorkouts addObject:wo]; [wo release]; } sqlite3_finalize(statement); } if(database) sqlite3_close(database); [query release]; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { //todaysWorkouts = [BIUtility todaysScheduledWorkouts]; static NSString *noteCellIdentifier = @"NoteCellIdentifier"; UITableViewCell *cell; if (indexPath.section < ([todaysWorkouts count])) { cell = [tableView dequeueReusableCellWithIdentifier:@"OtherCell"]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier: @"OtherCell"] autorelease]; cell.accessoryType = UITableViewCellAccessoryNone; } if (indexPath.row == 0) { Workout *wo = [todaysWorkouts objectAtIndex:indexPath.section]; [cell.textLabel setText:wo.workoutName]; } else { [cell.textLabel setText:@"Completed?"]; [cell.textLabel setFont:[UIFont fontWithName:@"Arial" size:15]]; [cell.textLabel setTextColor:[UIColor blueColor]]; } } else { cell = (NoteCell *)[tableView dequeueReusableCellWithIdentifier:noteCellIdentifier]; if (cell == nil) { NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"NoteCell" owner:self options:nil]; cell = [nib objectAtIndex:0]; } } return cell; //[cell release]; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSUInteger row = [indexPath row]; if (indexPath.section < ([todaysWorkouts count]) && (row == 0)) { MoveListViewController *moveListController = [[MoveListViewController alloc] initWithStyle:UITableViewStylePlain]; moveListController.workoutID = [[todaysWorkouts objectAtIndex:indexPath.section] workoutID]; moveListController.workoutName = [[todaysWorkouts objectAtIndex:indexPath.section] workoutName]; moveListController.woInstanceID = [[todaysWorkouts objectAtIndex:indexPath.section] woInstanceID]; NSLog(@"Workout Selected: %@", [[todaysWorkouts objectAtIndex:indexPath.section] workoutName]); Bring_ItAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; [delegate.workoutNavController pushViewController:moveListController animated:YES]; } else { UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath]; if (indexPath.section < ([todaysWorkouts count]) && (row == 1)) { if (cell.accessoryType == UITableViewCellAccessoryNone) { cell.accessoryType = UITableViewCellAccessoryCheckmark; } else { cell.accessoryType = UITableViewCellAccessoryNone; } } } [tableView deselectRowAtIndexPath:indexPath animated:YES]; } - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { NSInteger h = 35; return h; } - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return ([todaysWorkouts count] + 1); //return ([todaysWorkouts count]); } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { if (section < ([todaysWorkouts count])) { return 2; } else { return 1; } } - (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section { if (section < ([todaysWorkouts count])) { return @"Workout"; } else { return @"How Was Your Workout?"; } } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { [super viewDidUnload]; // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (void)dealloc { [todaysWorkouts release]; [bi release]; [super dealloc]; } @end

    Read the article

  • Why can i read dirty rows in MySql

    - by acidzombie24
    I cant believe this, i always throught the below would be concurrency safe. I write to a row in one transaction and i am able to read the dirty value from another transaction/command/connection! Why is this possible (not my main question) isnt this not desired and cause more troubles!?! Anyways, i expected that once i write to a row nothing else will be able to read to the row until the transaction is finished. And at least if the row can be still read that the clean (original) value will be read. (but maybe that would cause problems as well if the transaction doesnt use the newly commited data from the other transaction when it is ran) I would like count to == 11. I thought this would be safe in all variants of sql. What can i do to either 1) Not read the dirty value but clean 2) Have that row be locked until the transaction is finished? static MySqlConnection MakeConn() { string connStr = "server=192.168.126.128;user=root;database=TestDB;port=3306;password=a;"; MySqlConnection conn = new MySqlConnection(connStr); conn.Open(); return conn; } static Semaphore sem1 = new Semaphore(1, 1); static Semaphore sem2 = new Semaphore(1, 1); static void Main2() { Console.WriteLine("Starting Test"); // sem1.WaitOne(); Console.WriteLine("1W"); sem2.WaitOne(); Console.WriteLine("2W"); Thread oThread = new Thread(new ThreadStart(fn2)); oThread.Start(); var conn = MakeConn(); var cmd = new MySqlCommand(@" CREATE TABLE IF NOT EXISTS Persons ( P_Id int NOT NULL, name varchar(255), count int, PRIMARY KEY (P_Id) )", conn); cmd.ExecuteNonQuery(); cmd.CommandText = "delete from Persons; insert into Persons(name, count) VALUES('E', '4');"; cmd.ExecuteNonQuery(); cmd.CommandText = "select count from Persons;"; var count = (int)cmd.ExecuteScalar(); Console.WriteLine("Finish inserting. v={0}", count); sem2.Release(); Console.WriteLine("2R"); sem1.WaitOne(); Console.WriteLine("1W"); Console.WriteLine("Starting transaction"); using (var tns = conn.BeginTransaction()) { cmd.CommandText = "update Persons set count=count+1"; cmd.ExecuteNonQuery(); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); sem2.Release(); Console.WriteLine("2R"); sem1.WaitOne(); Console.WriteLine("1W"); count += 5; //10 cmd.CommandText = "update Persons set count=" + count.ToString(); cmd.ExecuteNonQuery(); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); tns.Commit(); } Console.WriteLine("finished transaction 1"); sem2.Release(); Console.WriteLine("2R"); sem1.WaitOne(); Console.WriteLine("1W"); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); sem2.Release(); Console.WriteLine("2R"); //sem1.WaitOne(); Console.WriteLine("1W"); } static void fn2() { int count; Console.WriteLine("Starting thread 2"); sem2.WaitOne(); Console.WriteLine("1W"); var conn = MakeConn(); var cmd = new MySqlCommand("", conn); sem1.Release(); Console.WriteLine("1R"); sem2.WaitOne(); Console.WriteLine("2W"); using (var tns = conn.BeginTransaction()) { cmd.CommandText = "update Persons set count=count+1"; cmd.ExecuteNonQuery(); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); sem1.Release(); Console.WriteLine("1R"); sem2.WaitOne(); Console.WriteLine("2W"); tns.Commit(); } Console.WriteLine("finished transaction 2"); sem1.Release(); Console.WriteLine("1R"); sem2.WaitOne(); Console.WriteLine("2W"); cmd.CommandText = "select count from Persons;"; count = (int)cmd.ExecuteScalar(); Console.WriteLine("count is {0}", count); //should be 11. 4 + 1x2(one each thread) += 5 from first thread == 11 sem1.Release(); Console.WriteLine("1R"); } console Starting Test 1W 2W Starting thread 2 Finish inserting. v=4 2R 1W 1R 1W Starting transaction count is 5 2R 2W count is 6 1R 1W count is 10 finished transaction 1 2R 2W finished transaction 2 1R 1W count is 10 2R 2W count is 10 1R

    Read the article

  • Table not Echoing out if another Table has a Zero value

    - by John
    Hello, The table below with mysql_query($sqlStr3) (the one with the word "Joined" in its row) does not echo if the result associated with mysql_query($sqlStr1) has a value of zero. This happens even if mysql_query($sqlStr3) returns a result. In other words, if a given loginid has an entry in the table "login", but not one in the table "submission", then the table associated with mysql_query($sqlStr3) does not echo. I don't understand why the "submission" table would have any effect on mysql_query($sqlStr3), since the $sqlStr3 only deals with another table, called "login", as seen below. Any ideas why this is happening? Thanks in advance, John W. <?php echo '<div class="profilename">User Profile for </div>'; echo '<div class="profilename2">'.$profile.'</div>'; $tzFrom = new DateTimeZone('America/New_York'); $tzTo = new DateTimeZone('America/Phoenix'); $profile = mysql_real_escape_string($_GET['profile']); $sqlStr = "SELECT l.username, l.loginid, s.loginid, s.submissionid, s.title, s.url, s.datesubmitted, s.displayurl FROM submission AS s INNER JOIN login AS l ON s.loginid = l.loginid WHERE l.username = '$profile' ORDER BY s.datesubmitted DESC"; $result = mysql_query($sqlStr); $arr = array(); echo "<table class=\"samplesrec1\">"; while ($row = mysql_fetch_array($result)) { $dt = new DateTime($row["datesubmitted"], $tzFrom); $dt->setTimezone($tzTo); echo '<tr>'; echo '<td class="sitename3">'.$dt->format('F j, Y &\nb\sp &\nb\sp g:i a').'</a></td>'; echo '<td class="sitename1"><a href="http://www.'.$row["url"].'">'.$row["title"].'</a></td>'; echo '</tr>'; } echo "</table>"; $sqlStr1 = "SELECT l.username, l.loginid, s.loginid, s.submissionid, s.title, s.url, s.datesubmitted, s.displayurl, l.created, count(s.submissionid) countSubmissions FROM submission AS s INNER JOIN login AS l ON s.loginid = l.loginid WHERE l.username = '$profile'"; $result1 = mysql_query($sqlStr1); $arr1 = array(); echo "<table class=\"samplesrec2\">"; while ($row1 = mysql_fetch_array($result1)) { echo '<tr>'; echo '<td class="sitename5">Submissions: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'.$row1["countSubmissions"].'</td>'; echo '</tr>'; } echo "</table>"; $sqlStr2 = "SELECT l.username, l.loginid, c.loginid, c.commentid, c.submissionid, c.comment, c.datecommented, l.created, count(c.commentid) countComments FROM comment AS c INNER JOIN login AS l ON c.loginid = l.loginid WHERE l.username = '$profile'"; $result2 = mysql_query($sqlStr2); $arr2 = array(); echo "<table class=\"samplesrec3\">"; while ($row2 = mysql_fetch_array($result2)) { echo '<tr>'; echo '<td class="sitename5">Comments: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'.$row2["countComments"].'</td>'; echo '</tr>'; } echo "</table>"; $tzFrom3 = new DateTimeZone('America/New_York'); $tzTo3 = new DateTimeZone('America/Phoenix'); $sqlStr3 = "SELECT created, username FROM login WHERE username = '$profile'"; $result3 = mysql_query($sqlStr3); $arr3 = array(); echo "<table class=\"samplesrec4\">"; while ($row3 = mysql_fetch_array($result3)) { $dt3 = new DateTime($row3["created"], $tzFrom3); $dt3->setTimezone($tzTo3); echo '<tr>'; echo '<td class="sitename5">Joined: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'.$dt->format('F j, Y').'</td>'; echo '</tr>'; } echo "</table>"; ?> </body> </html>

    Read the article

  • Saving image from Gallery to db - Coursor IllegalStateException

    - by MyWay
    I want to save to db some strings with image. Image can be taken from gallery or user can set the sample one. In the other activity I have a listview which should present the rows with image and name. I'm facing so long this problem. It occurs when I wanna display listview with the image from gallery, If the sample image is saved in the row everything works ok. My problem is similar to this one: how to save image taken from camera and show it to listview - crashes with "IllegalStateException" but I can't find there the solution for me My table in db looks like this: public static final String KEY_ID = "_id"; public static final String ID_DETAILS = "INTEGER PRIMARY KEY AUTOINCREMENT"; public static final int ID_COLUMN = 0; public static final String KEY_NAME = "name"; public static final String NAME_DETAILS = "TEXT NOT NULL"; public static final int NAME_COLUMN = 1; public static final String KEY_DESCRIPTION = "description"; public static final String DESCRIPTION_DETAILS = "TEXT"; public static final int DESCRIPTION_COLUMN = 2; public static final String KEY_IMAGE ="image" ; public static final String IMAGE_DETAILS = "BLOP"; public static final int IMAGE_COLUMN = 3; //method which create our table private static final String CREATE_PRODUCTLIST_IN_DB = "CREATE TABLE " + DB_TABLE + "( " + KEY_ID + " " + ID_DETAILS + ", " + KEY_NAME + " " + NAME_DETAILS + ", " + KEY_DESCRIPTION + " " + DESCRIPTION_DETAILS + ", " + KEY_IMAGE +" " + IMAGE_DETAILS + ");"; inserting statement: public long insertToProductList(String name, String description, byte[] image) { ContentValues value = new ContentValues(); // get the id of column and value value.put(KEY_NAME, name); value.put(KEY_DESCRIPTION, description); value.put(KEY_IMAGE, image); // put into db return db.insert(DB_TABLE, null, value); } Button which add the picture and onActivityResult method which saves the image and put it into the imageview public void AddPicture(View v) { // creating specified intent which have to get data Intent intent = new Intent(Intent.ACTION_PICK); // From where we want choose our pictures intent.setType("image/*"); startActivityForResult(intent, PICK_IMAGE); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { // TODO Auto-generated method stub super.onActivityResult(requestCode, resultCode, data); // if identification code match to the intent, //if yes we know that is our picture, if(requestCode ==PICK_IMAGE ) { // check if the data comes with intent if(data!= null) { Uri chosenImage = data.getData(); String[] filePathColumn = {MediaStore.Images.Media.DATA}; Cursor cursor = getContentResolver().query(chosenImage, filePathColumn, null, null, null); cursor.moveToFirst(); int columnIndex = cursor.getColumnIndex(filePathColumn[0]); String filePat = cursor.getString(columnIndex); cursor.close(); ImageOfProduct = BitmapFactory.decodeFile(filePat); if(ImageOfProduct!=null) { picture.setImageBitmap(ImageOfProduct); } messageDisplayer("got picture, isn't null " + IdOfPicture); } } } Then the code which converts bitmap to byte[] public byte[] bitmapToByteConvert(Bitmap bit ) { // stream of data getted for compressed bitmap ByteArrayOutputStream gettedData = new ByteArrayOutputStream(); // compressing method bit.compress(CompressFormat.PNG, 0, gettedData); // our byte array return gettedData.toByteArray(); } The method which put data to the row: byte[] image=null; // if the name isn't put to the editView if(name.getText().toString().trim().length()== 0) { messageDisplayer("At least you need to type name of product if you want add it to the DB "); } else{ String desc = description.getText().toString(); if(description.getText().toString().trim().length()==0) { messageDisplayer("the description is set as none"); desc = "none"; } DB.open(); if(ImageOfProduct!= null){ image = bitmapToByteConvert(ImageOfProduct); messageDisplayer("image isn't null"); } else { BitmapDrawable drawable = (BitmapDrawable) picture.getDrawable(); image = bitmapToByteConvert(drawable.getBitmap()); } if(image.length>0 && image!=null) { messageDisplayer(Integer.toString(image.length)); } DB.insertToProductList(name.getText().toString(), desc, image ); DB.close(); messageDisplayer("well done you add the product"); finish(); You can see that I'm checking here the length of array to be sure that I don't send empty one. And here is the place where Error appears imo, this code is from activity which presents the listview with data taken from db private void LoadOurLayoutListWithInfo() { // firstly wee need to open connection with db db= new sqliteDB(getApplicationContext()); db.open(); // creating our custom adaprer, the specification of it will be typed // in our own class (MyArrayAdapter) which will be created below ArrayAdapter<ProductFromTable> customAdapter = new MyArrayAdapter(); //get the info from whole table tablecursor = db.getAllColumns(); if(tablecursor != null) { startManagingCursor(tablecursor); tablecursor.moveToFirst(); } // now we moving all info from tablecursor to ourlist if(tablecursor != null && tablecursor.moveToFirst()) { do{ // taking info from row in table int id = tablecursor.getInt(sqliteDB.ID_COLUMN); String name= tablecursor.getString(sqliteDB.NAME_COLUMN); String description= tablecursor.getString(sqliteDB.DESCRIPTION_COLUMN); byte[] image= tablecursor.getBlob(3); tablefromDB.add(new ProductFromTable(id,name,description,image)); // moving until we didn't find last row }while(tablecursor.moveToNext()); } listView = (ListView) findViewById(R.id.tagwriter_listoftags); //as description says // setAdapter = The ListAdapter which is responsible for maintaining //the data backing this list and for producing a view to represent //an item in that data set. listView.setAdapter(customAdapter); } I put the info from row tho objects which are stored in list. I read tones of question but I can't find any solution for me. Everything works when I put the sample image ( which is stored in app res folder ). Thx for any advice

    Read the article

  • textbox disappears in paging - php

    - by fusion
    i'm calling the search.php page via ajax to search.html. the problem is, since i've implemented paging, the textbox with the search keyword from search.html 'disappears' when the user clicks the 'Next' button [because the page goes to search.php which has no textbox element] i'd like the textbox with the search keyword to be there, when the user goes through the records via paging. how'd i achieve this? search.html: <body> <form name="myform" class="wrapper"> <input type="text" name="q" onkeyup="showPage();" class="txt_search"/> <input type="button" name="button" onclick="showPage();" class="button"/> <p> <div id="txtHint"></div> <div id="page"></div> </form> </body> search.php [the relevant part]: $self = $_SERVER['PHP_SELF']; $limit = 5; //Number of results per page $numpages=ceil($totalrows/$limit); $query = $query." ORDER BY idQuotes LIMIT " . ($page-1)*$limit . ",$limit"; $result = mysql_query($query, $conn) or die('Error:' .mysql_error()); ?> <div class="caption">Search Results</div> <div class="center_div"> <table> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> <td style="text-align:right; font-size:15px;"><?php h($row['cArabic']); ?></td> <td style="font-size:16px;"><?php echo $cQuote; ?></td> <td style="font-size:12px;"><?php h($row['vAuthor']); ?></td> <td style="font-size:12px; font-style:italic; text-align:right;"><?php h($row['vReference']); ?></td> </tr> <?php } ?> </table> </div> <?php //Create and print the Navigation bar $nav=""; if($page > 1) { $nav .= "<a href=\"$self?page=" . ($page-1) . "&q=" .urlencode($search_result) . "\">< Prev</a>"; $first = "<a href=\"$self?page=1&q=" .urlencode($search_result) . "\"><< First</a>" ; } else { $nav .= "&nbsp;"; $first = "&nbsp;"; } for($i = 1 ; $i <= $numpages ; $i++) { if($i == $page) { $nav .= "<B>$i</B>"; }else{ $nav .= "<a href=\"$self?page=" . $i . "&q=" .urlencode($search_result) . "\">$i</a>"; } } if($page < $numpages) { $nav .= "<a href=\"$self?page=" . ($page+1) . "&q=" .urlencode($search_result) . "\">Next ></a>"; $last = "<a href=\"$self?page=$numpages&q=" .urlencode($search_result) . "\">Last >></a> "; } else { $nav .= "&nbsp;"; $last = "&nbsp;"; } echo "<br /><br />" . $first . $nav . $last; }

    Read the article

  • pagination in css/php

    - by fusion
    two questions: --1-- it displays all the number of pages. but i'd like it to display as: << Prev . . 3 4 [5] 6 7 . . Next --2-- when i hover on the current page no, it should change color or increase the font-size, but when i modify the css of a:hover, all the page nos change color or size instead of the one which i'm pointing to. also, when modifying a:active, nothing happens. this is my paging code in php: $self = $_SERVER['PHP_SELF']; $limit = 2; //Number of results per page $numpages=ceil($totalrows/$limit); $query = $query." ORDER BY idQuotes LIMIT " . ($page-1)*$limit . ",$limit"; $result = mysql_query($query, $conn) or die('Error:' .mysql_error()); ?> <div class="caption">Search Results</div> <div class="center_div"> <table> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> <td style="text-align:right; font-size:15px;"><?php h($row['cArabic']); ?></td> <td style="font-size:16px;"><?php echo $cQuote; ?></td> <td style="font-size:12px;"><?php h($row['vAuthor']); ?></td> <td style="font-size:12px; font-style:italic; text-align:right;"><?php h($row['vReference']); ?></td> </tr> <?php } ?> </table> </div> <div class="searchmain"> <?php //Create and print the Navigation bar $nav=""; $next = $page+1; $prev = $page-1; if($page > 1) { $nav .= "<span class=\"searchpage\"><a onclick=\"showPage('','$prev'); return false;\" href=\"$self?page=" . $prev . "&q=" .urlencode($search_result) . "\">< Prev</a></span>"; $first = "<span class=\"searchpage\"><a onclick=\"showPage('','1'); return false;\" href=\"$self?page=1&q=" .urlencode($search_result) . "\"> << </a></span>" ; } else { $nav .= "&nbsp;"; $first = "&nbsp;"; } for($i = 1 ; $i <= $numpages ; $i++) { if($i == $page) { $nav .= "<span class=\"searchpage\">$i</span>"; }else{ $nav .= "<span class=\"searchpage\"><a onclick=\"showPage('',$i); return false;\" href=\"$self?page=" . $i . "&q=" .urlencode($search_result) . "\">$i</a></span>"; } } if($page < $numpages) { $nav .= "<span class=\"searchpage\"><a onclick=\"showPage('','$next'); return false;\" href=\"$self?page=" . $next . "&q=" .urlencode($search_result) . "\">Next ></a></span>"; $last = "<span class=\"searchpage\"><a onclick=\"showPage('','$numpages'); return false;\" href=\"$self?page=$numpages&q=" .urlencode($search_result) . "\"> >> </a></span>"; } else { $nav .= "&nbsp;"; $last = "&nbsp;"; } echo $first . $nav . $last; ?> </div> and this is how it displays currently: css: .searchmain { margin:30px; text-align: center; } .searchpage { border: solid 1px #ddd; background: #fff; text-align:left; font-size: 16px; padding:9px 12px; color: #FEBE33; margin-left:2px; } .searchpage a{ text-decoration: none; color: #808080; } .searchpage a:hover { color: #FEBE33; border-color: #036; text-decoration: none; } .searchpage a:visited { color: #808080; }

    Read the article

  • HTML + javascript mouse over, mouseout, onclick not working in firefox.

    - by lucky
    Hello Everyone, My question is to get onMouseover,onMouseout,onMousedown,onClick on a table row. For which i am calling javascript userdefined functions. onMouseover --- Background color should change. onMouseout --- Reset to original color onClick --- First column checkbox/radio button should be set and background color should change onMousedown --- background color should change. My code in html is:- <tr onMouseOver="hover(this)" onMouseOut="hover_out(this)" onMouseDown="get_first_state(this)" onClick="checkit(this)" > and the methods in javascripts are:- var first_state = false; var oldcol = '#ffffff'; var oldcol_cellarray = new Array(); function hover(element) { if (! element) element = this; while (element.tagName != 'TR') { element = element.parentNode; } if (element.style.fontWeight != 'bold') { for (var i = 0; i<element.cells.length; i++) { if (element.cells[i].className != "no_hover") { oldcol_cellarray[i] = element.cells[i].style.backgroundColor; element.cells[i].style.backgroundColor='#e6f6f6'; } } } } // ----------------------------------------------------------------------------------------------- function hover_out(element) { if (! element) element = this; while (element.tagName != 'TR') { element = element.parentNode; } if (element.style.fontWeight != 'bold') { for (var i = 0; i<element.cells.length; i++) { if (element.cells[i].className != "no_hover") { if (typeof oldcol_cellarray != undefined) { element.cells[i].style.backgroundColor=oldcol_cellarray[i]; } else { element.cells[i].style.backgroundColor='#ffffff'; } //var oldcol_cellarray = new Array(); } } } } // ----------------------------------------------------------------------------------------------- function get_first_state(element) { while (element.tagName != 'TR') { element = element.parentNode; } first_state = element.cells[0].firstChild.checked; } // ----------------------------------------------------------------------------------------------- function checkit (element) { while (element.tagName != 'TR') { element = element.parentNode; } if (element.cells[0].firstChild.type == 'radio') { var typ = 0; } else if (element.cells[0].firstChild.type == 'checkbox') { typ = 1; } if (element.cells[0].firstChild.checked == true && typ == 1) { if (element.cells[0].firstChild.checked == first_state) { element.cells[0].firstChild.checked = false; } set_rowstyle(element, element.cells[0].firstChild.checked); } else { if (typ == 0 || element.cells[0].firstChild.checked == first_state) { element.cells[0].firstChild.checked = true; } set_rowstyle(element, element.cells[0].firstChild.checked); } if (typ == 0) { var table = element.parentNode; if (table.tagName != "TABLE") { table = table.parentNode; } if (table.tagName == "TABLE") { table=table.tBodies[0].rows; //var table = document.getElementById("js_tb").tBodies[0].rows; for (var i = 1; i< table.length; i++) { if (table[i].cells[0].firstChild.checked == true && table[i] != element) { table[i].cells[0].firstChild.checked = false; } if (table[i].cells[0].firstChild.checked == false) { set_rowstyle(table[i], false); } } } } } function set_rowstyle(r, on) { if (on == true) { for (var i =0; i < r.cells.length; i++) { r.style.fontWeight = 'bold'; r.cells[i].style.backgroundColor = '#f2f2c2'; } } else { for ( i =0; i < r.cells.length; i++) { r.style.fontWeight = 'normal'; r.cells[i].style.backgroundColor = '#ffffff'; } } } It is working as expected in IE. But coming to firefox i am surprised on seeing the output after so much of coding. In Firefox:-- onMouseOver is working as expected. color change of that particular row. onClick -- Setting the background color permenantly..eventhough i do onmouseover on different rows. the clicked previous row color is not reset to white. -- not as expected onclick on 2 rows..the background of both the rows is set..Only the latest row color should be set. other rows that are selected before should be set back..not as expected i.e if i click on all the rows..background color of everything is changed... Eventhough i click on the row. First column i.e radio button or checkbox is not set.. Please help me to solve this issue in firefox. Do let me know where my code needs to be changed... Thanks in advance!!

    Read the article

  • how to extract data from excel (apache poi) to put it in mysql table using jsp? [ SOLVED]

    - by Nihad KH
    I want to extract data from excel sheet to insert it into a mysql table using jsp, so far i've done this and its printing data into the outpout(using apache poi),what should i add to this code ? Output : Name Age Adress Mark 35 New york,AA Elise 22 India,bb Charlotte 45 France,cc Readexcel.jsp : <%@page import="java.sql.Statement"%> <%@page import="java.util.ArrayList"%> <%@page import="java.sql.PreparedStatement"%> <%@page import="java.sql.Connection"%> <%@page import="java.util.Date"%> <%@page import="org.apache.poi.ss.usermodel.Cell"%> <%@page import="org.apache.poi.ss.usermodel.Row"%> <%@page import="org.apache.poi.xssf.usermodel.XSSFSheet"%> <%@page import="org.apache.poi.xssf.usermodel.XSSFWorkbook"%> <%@page import="java.io.File"%> <%@page import="org.apache.commons.io.FilenameUtils"%> <%@page import="org.apache.commons.fileupload.FileItem"%> <%@page import="java.util.Iterator"%> <%@page import="java.util.List"%> <%@page import="org.apache.commons.fileupload.servlet.ServletFileUpload"%> <%@page import="org.apache.commons.fileupload.disk.DiskFileItemFactory"%> <%@page import="org.apache.commons.fileupload.FileItemFactory"%> <%@page contentType="text/html" pageEncoding="UTF-8"%> <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>PRINT DATA FROM EXCEL FILE</title> </head> <body> <% try{ boolean ismultipart=ServletFileUpload.isMultipartContent(request); if(!ismultipart){ }else{ FileItemFactory factory = new DiskFileItemFactory(); ServletFileUpload upload = new ServletFileUpload(factory); List items = null; try{ items = upload.parseRequest(request); }catch(Exception e){ } Iterator itr = items.iterator(); while(itr.hasNext()){ FileItem item = (FileItem)itr.next(); if(item.isFormField()){ }else{ String itemname = item.getName(); if((itemname==null || itemname.equals(""))){ continue; } String filename = FilenameUtils.getName(itemname); File f = checkExist(filename); item.write(f); try{ XSSFWorkbook workbook = new XSSFWorkbook(item.getInputStream()); XSSFSheet sheet = workbook.getSheetAt(0); Iterator<Row> rowIterator = sheet.iterator(); while (rowIterator.hasNext()){ Row row = rowIterator.next(); Iterator<Cell> cellIterator = row.cellIterator(); while (cellIterator.hasNext()) { Cell cell = cellIterator.next(); switch (cell.getCellType()){ case Cell.CELL_TYPE_NUMERIC: out.print(cell.getNumericCellValue() + "t"); break; case Cell.CELL_TYPE_STRING: out.print(cell.getStringCellValue() + "t"); break;} } out.println(""); } }catch (Exception e){ e.printStackTrace(); } } } } }catch(Exception e){ } finally { out.close(); } %> <%! private File checkExist(String fileName){ String saveFile = "D:/upload/"; File f = new File(saveFile+"/"+fileName); if(f.exists()){ StringBuffer sb = new StringBuffer(fileName); sb.insert(sb.lastIndexOf("."),"-"+new Date().getTime()); f = new File(saveFile+"/"+sb.toString()); } return f; } %> </body> </html> I've created a table in my database named EXCELDATA with the header of the excel sheet : ExcelData (Name varchar(50),age int,adress varchar(50)); what should i add to this code to get the data from the excel sheet to the mysql table ??

    Read the article

  • paging php error - undefined index

    - by fusion
    i've a search form with paging. when the user enters the keyword initially, it works fine and displays the required output; however, it also shows this error: Notice: Undefined index: page in C:\Users\user\Documents\Projects\Pro\search.php on line 21 Call Stack: 0.0011 372344 1. {main}() C:\Users\user\Documents\Projects\Pro\search.php:0 . .and if the user clicks on the 'next' page, it shows no output with this error thrown: Notice: Undefined index: q in C:\Users\user\Documents\Projects\Pro\search.php on line 19 Call Stack: 0.0016 372048 1. {main}() C:\Users\user\Documents\Projects\Pro\search.php:0 this is my code: <?php ini_set('display_errors',1); error_reporting(E_ALL|E_STRICT); include 'config.php'; $search_result = ""; $search_result = trim($_GET["q"]); $page= $_GET["page"]; //Get the page number to show if($page == "") $page=1; $search_result = mysql_real_escape_string($search_result); //Check if the string is empty if ($search_result == "") { echo "<p class='error'>Search Error. Please Enter Your Search Query.</p>" ; exit(); } if ($search_result == "%" || $search_result == "_" || $search_result == "+" ) { echo "<p class='error1'>Search Error. Please Enter a Valid Search Query.</p>" ; exit(); } if(!empty($search_result)) { // the table to search $table = "thquotes"; // explode search words into an array $arraySearch = explode(" ", $search_result); // table fields to search $arrayFields = array(0 => "cQuotes"); $countSearch = count($arraySearch); $a = 0; $b = 0; $query = "SELECT cQuotes, vAuthor, cArabic, vReference FROM ".$table." WHERE ("; $countFields = count($arrayFields); while ($a < $countFields) { while ($b < $countSearch) { $query = $query."$arrayFields[$a] LIKE '%$arraySearch[$b]%'"; $b++; if ($b < $countSearch) { $query = $query." AND "; } } $b = 0; $a++; if ($a < $countFields) { $query = $query.") OR ("; } } $query = $query.")"; $result = mysql_query($query, $conn) or die ('Error: '.mysql_error()); $totalrows = mysql_num_rows($result); if($totalrows < 1) { echo '<span class="error2">No matches found for "'.$search_result.'"</span>'; } else { $limit = 3; //Number of results per page $numpages=ceil($totalrows/$limit); $query = $query." ORDER BY idQuotes LIMIT " . ($page-1)*$limit . ",$limit"; $result = mysql_query($query, $conn) or die('Error:' .mysql_error()); ?> <div class="caption">Search Results</div> <div class="center_div"> <table> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> <td style="text-align:right; font-size:15px;"><?php h($row['cArabic']); ?></td> <td style="font-size:16px;"><?php echo $cQuote; ?></td> <td style="font-size:12px;"><?php h($row['vAuthor']); ?></td> <td style="font-size:12px; font-style:italic; text-align:right;"><?php h($row['vReference']); ?></td> </tr> <?php } ?> </table> </div> <?php //Create and print the Navigation bar $nav=""; if($page > 1) { $nav .= "<a href=\"search.php?page=" . ($page-1) . "&string=" .urlencode($search_result) . "\"><< Prev</a>"; } for($i = 1 ; $i <= $numpages ; $i++) { if($i == $page) { $nav .= "<B>$i</B>"; }else{ $nav .= "<a href=\"search.php?page=" . $i . "&string=" .urlencode($search_result) . "\">$i</a>"; } } if($page < $numpages) { $nav .= "<a href=\"search.php?page=" . ($page+1) . "&searchstring=" .urlencode($search_result) . "\">Next >></a>"; } echo "<br /><br />" . $nav; } } else { exit(); } ?>

    Read the article

  • pagination in php error

    - by fusion
    i've implemented this pagination class for my webpage in a separate file called class.pagination.php, but when i execute the page, nothing happens. it just displays a blank page. this is my search.php file, where i'm calling this class: <?php include 'config.php'; require ('class.pagination.php'); $search_result = ""; $search_result = $_GET["q"]; $search_result = trim($search_result); //Check if the string is empty if ($search_result == "") { echo "<p class='error'>Search Error. Please Enter Your Search Query.</p>" ; exit(); } //search query for multiple keywords if(!empty($search_result)) { // the table to search $table = "thquotes"; // explode search words into an array $arraySearch = explode(" ", $search_result); // table fields to search $arrayFields = array(0 => "cQuotes"); $countSearch = count($arraySearch); $a = 0; $b = 0; $query = "SELECT cQuotes, vAuthor, cArabic, vReference FROM ".$table." WHERE ("; $countFields = count($arrayFields); while ($a < $countFields) { while ($b < $countSearch) { $query = $query."$arrayFields[$a] LIKE '%$arraySearch[$b]%'"; $b++; if ($b < $countSearch) { $query = $query." AND "; } } $b = 0; $a++; if ($a < $countFields) { $query = $query.") OR ("; } } $query = $query.")"; $result = mysql_query($query, $conn) or die ('Error: '.mysql_error()); $totalrows = mysql_num_rows($result); if($totalrows < 1) { echo '<span class="error2">No matches found for "'.$search_result.'"</span>'; } else { ?> <div class="caption">Search Results</div> <div class="center_div"> <table> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> <td style="text-align:right; font-size:15px;"><?php h($row['cArabic']); ?></td> <td style="font-size:16px;"><?php echo $cQuote; ?></td> <td style="font-size:12px;"><?php h($row['vAuthor']); ?></td> <td style="font-size:12px; font-style:italic; text-align:right;"><?php h($row['vReference']); ?></td> </tr> <?php } ?> </table> </div> <?php } } else { exit(); } //Setting Pagination $pagination = new pagination(); $pagination->byPage = 5; $pagination->rows = $totalrows; // number of records in a table-back mysql_num_rows () instance or another, you have to play $from = $pagination->fromPagination(); // sql used for applications such LIMIT $ from, $ pagination-> byPage $pages = $pagination->pages(); if(isset($pages)) {?> <div class="pagination"> <?foreach ($pages as $key){?> <?if($key['current'] == 1) {?> <a href="?p=<?=$key['p']?>" class="active"><?=$key['page']?></a> <?} else {?> <a href="?p=<?=$key['p']?>" class="inactive"><?=$key['page']?></a> <?}?> <?}?> </div> <?} //End Pagination ?>

    Read the article

  • Mouse stops working after changing function

    - by heyohletsgo
    I'm making a console board game on c++, and i've been able to make the mouse work in the first function, the menu one, however, when i get to the getmove function and need to click on a house, it simply doesn't work.. Can anyone help? This is the class with the mouse. #include <cstdlib> #include <iostream> #include <process.h> #include <windows.h> #include <time.h> #include <stdio.h> using namespace std; void Game(); int Chu(); int rato(int &row, int &col) { HANDLE hIn; hIn = GetStdHandle(STD_INPUT_HANDLE); bool Continue = TRUE; INPUT_RECORD InRec; DWORD NumRead; HWND window = GetConsoleWindow(); POINT cursorPos; RECT wpos; int x = 0; int y = 0; //cout << hIn << endl; FlushConsoleInputBuffer(hIn); while (Continue) { ReadConsoleInput(hIn, &InRec, 1, &NumRead); switch (InRec.EventType) { case MOUSE_EVENT: if (GetAsyncKeyState(VK_LBUTTON)) { cout << "RATO"<<endl; GetWindowRect(window, &wpos); GetCursorPos(&cursorPos); cursorPos.x -= wpos.left; cursorPos.y -= wpos.top; x = (cursorPos.x - 5) / 16; y = (cursorPos.y - 25) / 24; cout << x << " " << y << endl; row = x; col = y; return row; } else if (GetAsyncKeyState(VK_RBUTTON)){ GetWindowRect(window, &wpos); GetCursorPos(&cursorPos); cursorPos.x -= wpos.left; cursorPos.y -= wpos.top; x = (cursorPos.x - 5) / 16; y = (cursorPos.y - 25) / 24; cout << x << " " << y << endl; row = x; col = y; return row; } break; } } } int main() { cout << "\n\n\n click on the stars" << endl; cout << " \n\n\n *******" << endl; int z = 0; int x = 0; int y = 0; int xo = 0; switch (rato(x,y)) { case 1: Game(); break; case 2: Game(); break; case 3: Game(); break; case 4: rato(x, y); break; case 5: rato(x, y); break; case 6: Game(); break; case 7: Game(); break; case 8: Game(); break; case 9: Game(); break; default: cout << "click again"; break; } return 0; } void Game() { int x = 0; int y = 0; int i = 0; cout << "GAME" << endl; do{ i++; rato(x, y); } while (i <= 2); Chu(); } int Chu() { int x = 0; int y = 0; int a = 0; int b = 0; int xo = 0; int yo = 0; cout << "\ click on the stars" << endl; HANDLE hConsole; hConsole = GetStdHandle(STD_OUTPUT_HANDLE); do{ xo = rato(x, y); if (0 <= xo && xo <= 5) { a = 1;} else cout << "CLICK AGAIN" << endl; } while (xo!=0); cout << a; return a; system("PAUSE"); }

    Read the article

  • The architecture and technologies to use for a secure, fast, reliable and easily scalable web application

    - by DSoul
    ^ For actual questions, skip to the lists down below I understand, that his is a vague topic, but please, before you turn the other way and disregard me, hear me out. I am currently doing research for a web application(I don't know if application is the correct word for it, but I will proceed w/ that for now), that one day might need to be everything mentioned in the title. I am bound by nothing. That means that every language, OS and framework is acceptable, but only if it proves it's usefulness. And if you are going to say, that scalability and speed depend on the code I write for this application, then I agree, but I am just trying to find something, that wouldn't stand in my way later on. I have done quite a bit reading on this subject, but I still don't have a clear picture, to what suits my needs, so I come to you, StackOverflow, to give me directions. I know you all must be wondering what I'm building, but I assure you, that it doesn't matter. I have heard of 12 factor app though, if you have any similar guidelines or what is, to suggest the please, go ahead. For the sake of keeping your answers as open as possible, I'm not gonna provide you my experience regarding anything written in this question. ^ Skippers, start here First off - the weights of the requirements are probably something like that (on a scale of 10): Security - 10 Speed - 5 Reliability (concurrency) - 7.5 Scalability - 10 Speed and concurrency are not a top priority, in the sense, that the program can be CPU intensive, and therefore slow, and only accept a not-that-high number of concurrent users, but both of these factors must be improvable by scaling the system Anyway, here are my questions: How many layers should the application have, so it would be future-proof and could best fulfill the aforementioned requirements? For now, what I have in mind is the most common version: Completely separated front end, that might be a web page or an MMI application or even both. Some middle-ware handling communication between the front and the back end. This is probably a server that communicates w/ the front end via HTTP. How the communication w/ the back end should be handled is probably dependent on the back end. The back end. Something that handles data through resources like DB and etc. and does various computations w/ the data. This, as the highest priority part of the software, must be easily spread to multiple computers later on and have no known security holes. I think ideally the middle-ware should send a request to a queue from where one of the back end processes takes this request, chops it up to smaller parts and buts these parts of the request back onto the same queue as the initial request, after what these parts will be then handled by other back end processes. Something *map-reduce*y, so to say. What frameworks, languages and etc. should these layers use? The technologies used here are not that important at this moment, you can ignore this part for now I've been pointed to node.js for this part. Do you guys know any better alternatives, or have any reasons why I should (not) use node.js for this particular job. I actually have no good idea, what to use for this job, there are too many options out there, so please direct me. This part (and the 2. one also, I think) depend a lot on the OS, so suggest any OSs alongside w/ the technologies/frameworks. Initially, all computers (or 1 for starters) hosting the back end are going to be virtual machines. Please do give suggestions to any part of the question, that you feel you have comprehensive knowledge and/or experience of. And also, point out if you feel that any part of the current set-up means an instant (or even distant) failure or if I missed a very important aspect to consider. I'm not looking for a definitive answer for how to achieve my goals, because there certainly isn't one, for I haven't provided you w/ all the required information. I'm just looking for recommendations and directions on what to look into. Also, bare in mind, that this isn't something that I have to get done quickly, to sell and let it be re-written by the new owner (which, I've been told for multiple times, is what I should aim for). I have all the time in the world and I really just want to learn doing something really high-end. Also, excuse me if my language isn't the best, I'm not a native. Anyway. Thanks in advance to anyone, who takes the time to help me out here. PS. When I do seem to come up w/ a good architecture/design for this project, I will certainly make it an open project and keep you guys up to date w/ it's development. As in what you could have told me earlier and etc. For obvious reasons the very same question got closed on SO, but could you guys still help me?.

    Read the article

  • problem in displays data in one page

    - by user318068
    hi ,,,,, I have a problem in the following code ... The following code works as follows displays the invites for each member so that if he had five invite from supposed to be displayed all on one page But before you code that does not function Proper image is the only display one invite on the page and until the approval or rejection of the invitation displays the invite the other .... But this is not my want to offer all on one page I wish I could solve the problem and I can view all calls in one page I think that the problem is in the order code I think that the problem is in the order code my code : <?php session_start(); if (!isset($_SESSION['user_id'])) { header("Location: login.php"); } $id=$_SESSION['user_id']; ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Untitled Document</title> </head> <body> <center> <?php include("connect.php"); $sql =mysql_query("select * from ninvite where recieverMemberID ='$id' and viwed= '0'"); $num =mysql_num_rows($sql); echo $num ; if ($num>0) { while($row=mysql_fetch_array($sql)) { $sender=$row['SenderMemberID']; $room=$row['RoomID']; $sql =mysql_query("select MemberName from members where MemberID ='$sender' "); $sql1 =mysql_query("select RoomName from rooms where RoomID ='$room' "); while($row=mysql_fetch_array($sql)) {$mem =$row['MemberName']; } while($rows=mysql_fetch_array($sql1)) { $Ro =$rows['RoomName']; ?> <form action="join.php" method="post"> <label> </label> <br/> <label> <?php echo " you have invite from $mem to join $Ro"; ?> </label> <br/><br/> <label>accept</label> <input name="radio1" type="radio" value="accpet" /> <label>reject</label> <input name="radio1" type="radio" value="Reject" /><br/> <input type="submit" name="submit" value="done" /> </form> <?php } } } ?> </center> </body> </html> thanks alot. my SQl -- phpMyAdmin SQL Dump -- version 3.2.4 -- http://www.phpmyadmin.net -- Host: localhost -- Generation Time: May 07, 2010 at 12:50 ? -- Server version: 5.1.41 -- PHP Version: 5.3.1 SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO"; /*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT /; /!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS /; /!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION /; /!40101 SET NAMES utf8 */; -- -- Database: tr -- -- Table structure for table joinroom CREATE TABLE IF NOT EXISTS joinroom ( MemberID int(10) NOT NULL, RoomID int(10) NOT NULL, PRIMARY KEY (MemberID,RoomID) ) ENGINE=MyISAM DEFAULT CHARSET=latin1; -- -- Dumping data for table joinroom INSERT INTO joinroom (MemberID, RoomID) VALUES (28, 1); -- -- Table structure for table members CREATE TABLE IF NOT EXISTS members ( MemberID int(10) unsigned NOT NULL AUTO_INCREMENT, MemberName varchar(20) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, MemberPass varchar(10) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, MemberEmail varchar(30) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, MemberLocation text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, MemberImg text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, PRIMARY KEY (MemberID) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=34 ; -- -- Dumping data for table members INSERT INTO members (MemberID, MemberName, MemberPass, MemberEmail, MemberLocation, MemberImg) VALUES (28, 'marwa', '1234', '[email protected]', 'mmmmmm', 'dddddddddd'), (29, 'nora', '1234', '[email protected]', 'fffffffffffgg', 'gggggggggggggg'), (30, 'soso', '1234', '[email protected]', 'ffffffff', 'kkkkkkkkkkkkkkkkkk'), (31, 'gege', '1234', '[email protected]', 'kkkkkkkkkkkkkkkk', 'uuuuuuuuuuuuuuuuu'), (32, 'nono', '1234', '[email protected]', 'ggggggggggggaaaaa', 'aaaaaaaaaaaaaaa'), (33, 'nda', '1234', '[email protected]', 'kkkkkkkkkkkkkkkk', 'ooooooooooooooo'); -- -- Table structure for table ninvite CREATE TABLE IF NOT EXISTS ninvite ( SenderMemberID int(11) NOT NULL AUTO_INCREMENT, recieverMemberID varchar(30) NOT NULL, RoomID int(11) NOT NULL, viwed int(11) NOT NULL, PRIMARY KEY (SenderMemberID,recieverMemberID,RoomID) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=33 ; -- -- Dumping data for table ninvite INSERT INTO ninvite (SenderMemberID, recieverMemberID, RoomID, viwed) VALUES (28, '33', 1, 0), (28, '32', 1, 0), (28, '31', 1, 0); /*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT /; /!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS /; /!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

    Read the article

  • Inequality joins, Asynchronous transformations and Lookups : SSIS

    - by jamiet
    It is pretty much accepted by SQL Server Integration Services (SSIS) developers that synchronous transformations are generally quicker than asynchronous transformations (for a description of synchronous and asynchronous transformations go read Asynchronous and synchronous data flow components). Notice I said “generally” and not “always”; there are circumstances where using asynchronous transformations can be beneficial and in this blog post I’ll demonstrate such a scenario, one that is pretty common when building data warehouses. Imagine I have a [Customer] dimension table that manages information about all of my customers as a slowly-changing dimension. If that is a type 2 slowly changing dimension then you will likely have multiple rows per customer in that table. Furthermore you might also have datetime fields that indicate the effective time period of each member record. Here is such a table that contains data for four dimension members {Terry, Max, Henry, Horace}: Notice that we have multiple records per customer and that the [SCDStartDate] of a record is equivalent to the [SCDEndDate] of the record that preceded it (if there was one). (Note that I am on record as saying I am not a fan of this technique of storing an [SCDEndDate] but for the purposes of clarity I have included it here.) Anyway, the idea here is that we will have some incoming data containing [CustomerName] & [EffectiveDate] and we need to use those values to lookup [Customer].[CustomerId]. The logic will be: Lookup a [CustomerId] WHERE [CustomerName]=[CustomerName] AND [SCDStartDate] <= [EffectiveDate] AND [EffectiveDate] <= [SCDEndDate] The conventional approach to this would be to use a full cached lookup but that isn’t an option here because we are using inequality conditions. The obvious next step then is to use a non-cached lookup which enables us to change the SQL statement to use inequality operators: Let’s take a look at the dataflow: Notice these are all synchronous components. This approach works just fine however it does have the limitation that it has to issue a SQL statement against your lookup set for every row thus we can expect the execution time of our dataflow to increase linearly in line with the number of rows in our dataflow; that’s not good. OK, that’s the obvious method. Let’s now look at a different way of achieving this using an asynchronous Merge Join transform coupled with a Conditional Split. I’ve shown it post-execution so that I can include the row counts which help to illustrate what is going on here: Notice that there are more rows output from our Merge Join component than on the input. That is because we are joining on [CustomerName] and, as we know, we have multiple records per [CustomerName] in our lookup set. Notice also that there are two asynchronous components in here (the Sort and the Merge Join). I have embedded a video below that compares the execution times for each of these two methods. The video is just over 8minutes long. View on Vimeo  For those that can’t be bothered watching the video I’ll tell you the results here. The dataflow that used the Lookup transform took 36 seconds whereas the dataflow that used the Merge Join took less than two seconds. An illustration in case it is needed: Pretty conclusive proof that in some scenarios it may be quicker to use an asynchronous component than a synchronous one. Your mileage may of course vary. The scenario outlined here is analogous to performance tuning procedural SQL that uses cursors. It is common to eliminate cursors by converting them to set-based operations and that is effectively what we have done here. Our non-cached lookup is performing a discrete operation for every single row of data, exactly like a cursor does. By eliminating this cursor-in-disguise we have dramatically sped up our dataflow. I hope all of that proves useful. You can download the package that I demonstrated in the video from my SkyDrive at http://cid-550f681dad532637.skydrive.live.com/self.aspx/Public/BlogShare/20100514/20100514%20Lookups%20and%20Merge%20Joins.zip Comments are welcome as always. @Jamiet Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

    Read the article

  • July, the 31 Days of SQL Server DMO’s – Day 22 (sys.dm_db_index_physical_stats)

    - by Tamarick Hill
    The sys.dm_db_index_physical_stats Dynamic Management Function is used to return information about the fragmentation levels, page counts, depth, number of levels, record counts, etc. about the indexes on your database instance. One row is returned for each level in a given index, which we will discuss more later. The function takes a total of 5 input parameters which are (1) database_id, (2) object_id, (3) index_id, (4) partition_number, and (5) the mode of the scan level that you would like to run. Let’s use this function with our AdventureWorks2012 database to better illustrate the information it provides. SELECT * FROM sys.dm_db_index_physical_stats(db_id('AdventureWorks2012'), NULL, NULL, NULL, NULL) As you can see from the result set, there is a lot of beneficial information returned from this DMF. The first couple of columns in the result set (database_id, object_id, index_id, partition_number, index_type_desc, alloc_unit_type_desc) are either self-explanatory or have been explained in our previous blog sessions so I will not go into detail about these at this time. The next column in the result set is the index_depth which represents how deep the index goes. For example, If we have a large index that contains 1 root page, 3 intermediate levels, and 1 leaf level, our index depth would be 5. The next column is the index_level which refers to what level (of the depth) a particular row is referring to. Next is probably one of the most beneficial columns in this result set, which is the avg_fragmentation_in_percent. This column shows you how fragmented a particular level of an index may be. Many people use this column within their index maintenance jobs to dynamically determine whether they should do REORG’s or full REBUILD’s of a given index. The fragment count represents the number of fragments in a leaf level while the avg_fragment_size_in_pages represents the number of pages in a fragment. The page_count column tells you how many pages are in a particular index level. From my result set above, you see the the remaining columns all have NULL values. This is because I did not specify a ‘mode’ in my query and as a result it used the ‘LIMITED’ mode by default. The LIMITED mode is meant to be lightweight so it does collect information for every column in the result set. I will re-run my query again using the ‘DETAILED’ mode and you will see we now have results for these rows. SELECT * FROM sys.dm_db_index_physical_stats(db_id('AdventureWorks2012'), NULL, NULL, NULL, ‘DETAILED’)   From the remaining columns, you see we get even more detailed information such as how many records are in a particular index level (record_count). We have a column for ghost_record_count which represents the number of records that have been marked for deletion, but have not physically been removed by the background ghost cleanup process. We later see information on the MIN, MAX, and AVG record size in bytes. The forwarded_record_count column refers to records that have been updated and now no longer fit within the row on the page anymore and thus have to be moved. A forwarded record is left in the original location with a pointer to the new location. The last column in the result set is the compressed_page_count column which tells you how many pages in your index have been compressed. This is a very powerful DMF that returns good information about the current indexes in your system. However, based on the mode you select, it could be a very resource intensive function so be careful with how you use it. For more information on this Dynamic Management Function, please see the below Books Online link: http://msdn.microsoft.com/en-us/library/ms188917.aspx Follow me on Twitter @PrimeTimeDBA

    Read the article

  • SQL SERVER – Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012

    - by pinaldave
    SQL Server 2012 introduces new analytical function LEAD() and LAG(). This functions accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. When we look at above resultset it is very clear that LEAD function gives us value which is going to come in next line and LAG function gives us value which was encountered in previous line. If we have to generate the same result without using this function we will have to use self join. In future blog post we will see the same. Let us explore this function a bit more. This function not only provide previous or next line but it can also access any line before or after using offset. Let us fun following query, where LEAD and LAG function accesses the row with offset of 2. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. You can see the LEAD and LAG functions  now have interval of  rows when they are returning results. As there is interval of two rows the first two rows in LEAD function and last two rows in LAG function will return NULL value. You can easily replace this NULL Value with any other default value by passing third parameter in LEAD and LAG function. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where NULL are now replaced with value 0. Just like any other analytic function we can easily partition this function as well. Let us see the use of PARTITION BY in this clause. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where now the data is partitioned by SalesOrderID and LEAD and LAG functions are returning the appropriate result in that window. As now there are smaller partition in my query, you will see higher presence of NULL. In future blog post we will see how this functions are compared to SELF JOIN. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • perl comparing 2 data file as array 2D for finding match one to one [migrated]

    - by roman serpa
    I'm doing a program that uses combinations of variables ( combiData.txt 63 rows x different number of columns) for analysing a data table ( j1j2_1.csv, 1000filas x 19 columns ) , to choose how many times each combination is repeated in data table and which rows come from (for instance, tableData[row][4]). I have tried to compile it , however I get the following message : Use of uninitialized value $val in numeric eq (==) at rowInData.pl line 34. Use of reference "ARRAY(0x1a2eae4)" as array index at rowInData.pl line 56. Use of reference "ARRAY(0x1a1334c)" as array index at rowInData.pl line 56. Use of uninitialized value in subtraction (-) at rowInData.pl line 56. Modification of non-creatable array value attempted, subscript -1 at rowInData.pl line 56. nothing This is my code: #!/usr/bin/perl use strict; use warnings; my $line_match; my $countTrue; open (FILE1, "<combiData.txt") or die "can't open file text1.txt\n"; my @tableCombi; while(<FILE1>) { my @row = split(' ', $_); push(@tableCombi, \@row); } close FILE1 || die $!; open (FILE2, "<j1j2_1.csv") or die "can't open file text1.txt\n"; my @tableData; while(<FILE2>) { my @row2 = split(/\s*,\s*/, $_); push(@tableData, \@row2); } close FILE2 || die $!; #function transform combiData.txt variable (position ) to the real value that i have to find in the data table. sub trueVal($){ my ($val) = $_[0]; if($val == 7){ return ('nonsynonymous_SNV'); } elsif( $val == 14) { return '1'; } elsif( $val == 15) { return '1';} elsif( $val == 16) { return '1'; } elsif( $val == 17) { return '1'; } elsif( $val == 18) { return '1';} elsif( $val == 19) { return '1';} else { print 'nothing'; } } #function IntToStr ( ) , i'm not sure if it is necessary) that transforms $ to strings , to use the function <eq> in the third loop for the array of combinations compared with the data array . sub IntToStr { return "$_[0]"; } for my $combi (@tableCombi) { $line_match = 0; for my $sheetData (@tableData) { $countTrue=0; for my $cell ( @$combi) { #my $temp =\$tableCombi[$combi][$cell] ; #if ( trueVal($tableCombi[$combi][$cell] ) eq $tableData[$sheetData][ $tableCombi[$combi][$cell] - 1 ] ){ #if ( IntToStr(trueVal($$temp )) eq IntToStr( $tableData[$sheetData][ $$temp-1] ) ){ if ( IntToStr(trueVal($tableCombi[$combi][$cell]) ) eq IntToStr($tableData[$sheetData][ $tableCombi[$combi][$cell] -1]) ){ $countTrue++;} if ($countTrue==@$combi){ $line_match++; #if ($line_match < 50){ print $tableData[$sheetData][4]." "; #} } } } print $line_match." \n"; }

    Read the article

  • Is there a theory for "transactional" sequences of failing and no-fail actions?

    - by Ross Bencina
    My question is about writing transaction-like functions that execute sequences of actions, some of which may fail. It is related to the general C++ principle "destructors can't throw," no-fail property, and maybe also with multi-phase transactions or exception safety. However, I'm thinking about it in language-neutral terms. My concern is with correctly designing error handling in C++ functions that must be reliable. I would like to know what the concepts below are called so that I can learn more about them. I'm sorry that I can't ask the question more directly. Since I don't know this area I have provided an example to explain my question. The question is at the end. Here goes: Consider a sequence of steps or actions executed sequentially, where actions belong to one of two classes: those that always succeed, and those that may fail. In the examples below: S stands for an action that always succeeds (called "no-fail" in some settings). F stands for an action that may fail (for example, it might fail to allocate memory or do I/O that could fail). Consider a sequences of actions (executed sequentially from left to right): S->S->S->S Since each action in the sequence above succeeds, the whole sequence succeeds. On the other hand, the following sequence may fail because the last action may fail: S->S->S->F So, claim: a sequence has the no-fail (S) property if and only if all of its actions are no-fail. Now, I'm interested in action sequences that form "atomic transactions", with "failure atomicity," i.e. where either the whole sequence completes successfully, or there is no effect. I.e. if some action fails, the earlier ones must be rolled back. This requires that any successfully executed actions prior to a failing action must always be able to be rolled back. Consider the sequence: S->S->S->F S<-S<-S In the example above, the first row is the forward path of the transaction, and the second row are inverse actions (executed from right to left) that can be used to roll back if the final top row actions fails. It seems to me that for a transaction to support failure atomicity, the following invariant must hold: Claim: To support failure atomicity (either completion or complete roll-back on failure) all actions preceding the latest failable (F) action on the forward path (marked * in the example below) must have no-fail (S) inverses. The following is an example of a sequence that supports failure atomicity: * S->F->F->F S<-S<-S Further, if we want the transaction to be able to attempt cancellation mid-way through, but still guarantee either full completion or full rollback then we need the following property: Claim: To support failure atomicity and cancellation mid-way through execution, in the face of errors in the inverse (cancellation) path, all actions following the earliest failable (F) inverse on the reverse path (marked *) must be no-fail (S). F->F->F->S->S S<-S<-F<-F * I believe that these two conditions guarantee that an abortable/cancelable transaction will never get "stuck". My questions are: What is the study and theory of these properties called? are my claims correct? and what else is there to know? UPDATE 1: Updated terminology: what I previously called "robustness" is called atomicity in the database literature. UPDATE 2: Added explicit reference to failure atomicity, which seems to be a thing.

    Read the article

  • Styling specific columns and rows

    - by hattenn
    I'm trying to style some specific parts of a 5x4 table that I create. It should be like this: Every even numbered row and every odd numbered row should get a different color. Text in the second, third, and fourth columns should be centered. I have this table: <table> <caption>Some caption</caption> <colgroup> <col> <col class="value"> <col class="value"> <col class="value"> </colgroup> <thead> <tr> <th id="year">Year</th> <th>1999</th> <th>2000</th> <th>2001</th> </tr> </thead> <tbody> <tr class="oddLine"> <td>Berlin</td> <td>3,3</td> <td>1,9</td> <td>2,3</td> </tr> <tr class="evenLine"> <td>Hamburg</td> <td>1,5</td> <td>1,3</td> <td>2,0</td> </tr> <tr class="oddLine"> <td>München</td> <td>0,6</td> <td>1,1</td> <td>1,0</td> </tr> <tr class="evenLine"> <td>Frankfurt</td> <td>1,3</td> <td>1,6</td> <td>1,9</td> </tr> </tbody> <tfoot> <tr class="oddLine"> <td>Total</td> <td>6,7</td> <td>5,9</td> <td>7,2</td> </tr> </tfoot> </table> And I have this CSS file: table, th, td { border: 1px solid black; border-collapse: collapse; padding: 0px 5px; } #year { text-align: left; } .oddLine { background-color: #DDDDDD; } .evenLine { background-color: #BBBBBB; } .value { text-align: center; } And this doesn't work. The text in the columns are not centered. What is the problem here? And is there a way to solve it (other than changing the class of all the cells that I want centered)? P.S.: I think there's some interference with .evenLine and .oddLine classes. Because when I put "background: black" in the class "value", it changes the background color of the columns in the first row. The thing is, if I delete those two classes, text-align still doesn't work, but background attribute works perfectly. Argh...

    Read the article

  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

    Read the article

  • 10 Essential Tools for building ASP.NET Websites

    - by Stephen Walther
    I recently put together a simple public website created with ASP.NET for my company at Superexpert.com. I was surprised by the number of free tools that I ended up using to put together the website. Therefore, I thought it would be interesting to create a list of essential tools for building ASP.NET websites. These tools work equally well with both ASP.NET Web Forms and ASP.NET MVC. Performance Tools After reading Steve Souders two (very excellent) books on front-end website performance High Performance Web Sites and Even Faster Web Sites, I have been super sensitive to front-end website performance. According to Souders’ Performance Golden Rule: “Optimize front-end performance first, that's where 80% or more of the end-user response time is spent” You can use the tools below to reduce the size of the images, JavaScript files, and CSS files used by an ASP.NET application. 1. Sprite and Image Optimization Framework CSS sprites were first described in an article written for A List Apart entitled CSS sprites: Image Slicing’s Kiss of Death. When you use sprites, you combine multiple images used by a website into a single image. Next, you use CSS trickery to display particular sub-images from the combined image in a webpage. The primary advantage of sprites is that they reduce the number of requests required to display a webpage. Requesting a single large image is faster than requesting multiple small images. In general, the more resources – images, JavaScript files, CSS files – that must be moved across the wire, the slower your website. However, most people avoid using sprites because they require a lot of work. You need to combine all of the images and write just the right CSS rules to display the sub-images. The Microsoft Sprite and Image Optimization Framework enables you to avoid all of this work. The framework combines the images for you automatically. Furthermore, the framework includes an ASP.NET Web Forms control and an ASP.NET MVC helper that makes it easy to display the sub-images. You can download the Sprite and Image Optimization Framework from CodePlex at http://aspnet.codeplex.com/releases/view/50869. The Sprite and Image Optimization Framework was written by Morgan McClean who worked in the office next to mine at Microsoft. Morgan was a scary smart Intern from Canada and we discussed the Framework while he was building it (I was really excited to learn that he was working on it). Morgan added some great advanced features to this framework. For example, the Sprite and Image Optimization Framework supports something called image inlining. When you use image inlining, the actual image is stored in the CSS file. Here’s an example of what image inlining looks like: .Home_StephenWalther_small-jpg { width:75px; height:100px; background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAEsAAABkCAIAAABB1lpeAAAAB GdBTUEAALGOfPtRkwAAACBjSFJNAACHDwAAjA8AAP1SAACBQAAAfXkAAOmLAAA85QAAGcxzPIV3AAAKL s+zNfREAAAAASUVORK5CYII=) no-repeat 0% 0%; } The actual image (in this case a picture of me that is displayed on the home page of the Superexpert.com website) is stored in the CSS file. If you visit the Superexpert.com website then very few separate images are downloaded. For example, all of the images with a red border in the screenshot below take advantage of CSS sprites: Unfortunately, there are some significant Gotchas that you need to be aware of when using the Sprite and Image Optimization Framework. There are workarounds for these Gotchas. I plan to write about these Gotchas and workarounds in a future blog entry. 2. Microsoft Ajax Minifier Whenever possible you should combine, minify, compress, and cache with a far future header all of your JavaScript and CSS files. The Microsoft Ajax Minifier makes it easy to minify JavaScript and CSS files. Don’t confuse minification and compression. You need to do both. According to Souders, you can reduce the size of a JavaScript file by an additional 20% (on average) by minifying a JavaScript file after you compress the file. When you minify a JavaScript or CSS file, you use various tricks to reduce the size of the file before you compress the file. For example, you can minify a JavaScript file by replacing long JavaScript variables names with short variables names and removing unnecessary white space and comments. You can minify a CSS file by doing such things as replacing long color names such as #ffffff with shorter equivalents such as #fff. The Microsoft Ajax Minifier was created by Microsoft employee Ron Logan. Internally, this tool was being used by several large Microsoft websites. We also used the tool heavily on the ASP.NET team. I convinced Ron to publish the tool on CodePlex so that everyone in the world could take advantage of it. You can download the tool from the ASP.NET Ajax website and read documentation for the tool here. I created the installer for the Microsoft Ajax Minifier. When creating the installer, I also created a Visual Studio build task to make it easy to minify all of your JavaScript and CSS files whenever you do a build within Visual Studio automatically. Read the Ajax Minifier Quick Start to learn how to configure the build task. 3. ySlow The ySlow tool is a free add-on for Firefox created by Yahoo that enables you to test the front-end of your website. For example, here are the current test results for the Superexpert.com website: The Superexpert.com website has an overall score of B (not perfect but not bad). The ySlow tool is not perfect. For example, the Superexpert.com website received a failing grade of F for not using a Content Delivery Network even though the website using the Microsoft Ajax Content Delivery Network for JavaScript files such as jQuery. Uptime After publishing a website live to the world, you want to ensure that the website does not encounter any issues and that it stays live. I use the following tools to monitor the Superexpert.com website now that it is live. 4. ELMAH ELMAH stands for Error Logging Modules and Handlers for ASP.NET. ELMAH enables you to record any errors that happen at your website so you can review them in the future. You can download ELMAH for free from the ELMAH project website. ELMAH works great with both ASP.NET Web Forms and ASP.NET MVC. You can configure ELMAH to store errors in a number of different stores including XML files, the Event Log, an Access database, a SQL database, an Oracle database, or in computer RAM. You also can configure ELMAH to email error messages to you when they happen. By default, you can access ELMAH by requesting the elmah.axd page from a website with ELMAH installed. Here’s what the elmah page looks like from the Superexpert.com website (this page is password-protected because secret information can be revealed in an error message): If you click on a particular error message, you can view the original Yellow Screen ASP.NET error message (even when the error message was never displayed to the actual user). I installed ELMAH by taking advantage of the new package manager for ASP.NET named NuGet (originally named NuPack). You can read the details about NuGet in the following blog entry by Scott Guthrie. You can download NuGet from CodePlex. 5. Pingdom I use Pingdom to verify that the Superexpert.com website is always up. You can sign up for Pingdom by visiting Pingdom.com. You can use Pingdom to monitor a single website for free. At the Pingdom website, you configure the frequency that your website gets pinged. I verify that the Superexpert.com website is up every 5 minutes. I have the Pingdom service verify that it can retrieve the string “Contact Us” from the website homepage. If your website goes down, you can configure Pingdom so that it sends an email, Twitter, SMS, or iPhone alert. I use the Pingdom iPhone app which looks like this: 6. Host Tracker If your website does go down then you need some way of determining whether it is a problem with your local network or if your website is down for everyone. I use a website named Host-Tracker.com to check how badly a website is down. Here’s what the Host-Tracker website displays for the Superexpert.com website when the website can be successfully pinged from everywhere in the world: Notice that Host-Tracker pinged the Superexpert.com website from 68 locations including Roubaix, France and Scranton, PA. Debugging I mean debugging in the broadest possible sense. I use the following tools when building a website to verify that I have not made a mistake. 7. HTML Spell Checker Why doesn’t Visual Studio have a built-in spell checker? Don’t know – I’ve always found this mysterious. Fortunately, however, a former member of the ASP.NET team wrote a free spell checker that you can use with your ASP.NET pages. I find a spell checker indispensible. It is easy to delude yourself that you are capable of perfect spelling. I’m always super embarrassed when I actually run the spell checking tool and discover all of my spelling mistakes. The fastest way to add the HTML Spell Checker extension to Visual Studio is to select the menu option Tools, Extension Manager within Visual Studio. Click on Online Gallery and search for HTML Spell Checker: 8. IIS SEO Toolkit If people cannot find your website through Google then you should not even bother to create it. Microsoft has a great extension for IIS named the IIS Search Engine Optimization Toolkit that you can use to identify issue with your website that would hurt its page rank. You also can use this tool to quickly create a sitemap for your website that you can submit to Google or Bing. You can even generate the sitemap for an ASP.NET MVC website. Here’s what the report overview for the Superexpert.com website looks like: Notice that the Sueprexpert.com website had plenty of violations. For example, there are 65 cases in which a page has a broken hyperlink. You can drill into these violations to identity the exact page and location where these violations occur. 9. LinqPad If your ASP.NET website accesses a database then you should be using LINQ to Entities with the Entity Framework. Using LINQ involves some magic. LINQ queries written in C# get converted into SQL queries for you. If you are not careful about how you write your LINQ queries, you could unintentionally build a really badly performing website. LinqPad is a free tool that enables you to experiment with your LINQ queries. It even works with Microsoft SQL CE 4 and Azure. You can use LinqPad to execute a LINQ to Entities query and see the results. You also can use it to see the resulting SQL that gets executed against the database: 10. .NET Reflector I use .NET Reflector daily. The .NET Reflector tool enables you to take any assembly and disassemble the assembly into C# or VB.NET code. You can use .NET Reflector to see the “Source Code” of an assembly even when you do not have the actual source code. You can download a free version of .NET Reflector from the Redgate website. I use .NET Reflector primarily to help me understand what code is doing internally. For example, I used .NET Reflector with the Sprite and Image Optimization Framework to better understand how the MVC Image helper works. Here’s part of the disassembled code from the Image helper class: Summary In this blog entry, I’ve discussed several of the tools that I used to create the Superexpert.com website. These are tools that I use to improve the performance, improve the SEO, verify the uptime, or debug the Superexpert.com website. All of the tools discussed in this blog entry are free. Furthermore, all of these tools work with both ASP.NET Web Forms and ASP.NET MVC. Let me know if there are any tools that you use daily when building ASP.NET websites.

    Read the article

  • Reactive Extensions vs FileSystemWatcher

    - by Joel Mueller
    One of the things that has long bugged me about the FileSystemWatcher is the way it fires multiple events for a single logical change to a file. I know why it happens, but I don't want to have to care - I just want to reparse the file once, not 4-6 times in a row. Ideally, there would be an event that only fires when a given file is done changing, rather than every step along the way. Over the years I've come up with various solutions to this problem, of varying degrees of ugliness. I thought Reactive Extensions would be the ultimate solution, but there's something I'm not doing right, and I'm hoping someone can point out my mistake. I have an extension method: public static IObservable<IEvent<FileSystemEventArgs>> GetChanged(this FileSystemWatcher that) { return Observable.FromEvent<FileSystemEventArgs>(that, "Changed"); } Ultimately, I would like to get one event per filename, within a given time period - so that four events in a row with a single filename are reduced to one event, but I don't lose anything if multiple files are modified at the same time. BufferWithTime sounds like the ideal solution. var bufferedChange = watcher.GetChanged() .Select(e => e.EventArgs.FullPath) .BufferWithTime(TimeSpan.FromSeconds(1)) .Where(e => e.Count > 0) .Select(e => e.Distinct()); When I subscribe to this observable, a single change to a monitored file triggers my subscription method four times in a row, which rather defeats the purpose. If I remove the Distinct() call, I see that each of the four calls contains two identical events - so there is some buffering going on. Increasing the TimeSpan passed to BufferWithTime seems to have no effect - I went as high as 20 seconds without any change in behavior. This is my first foray into Rx, so I'm probably missing something obvious. Am I doing it wrong? Is there a better approach? Thanks for any suggestions...

    Read the article

  • OpenXML SDK: Make Excel recalculate formula

    - by chiccodoro
    I update some cells of an Excel spreadsheet through the Microsoft Office OpenXML SDK 2.0. Changing the values makes all cells containing formula that depend on the changed cells invalid. However, due to the cached values Excel does not recalculate the formular, even if the user clicks on "Calculate now". What is the best way to invalidate all dependent cells of the whole workbook through the SDK? So far, I've found the following code snippet at http://cdonner.com/introduction-to-microsofts-open-xml-format-sdk-20-with-a-focus-on-excel-documents.htm: public static void ClearAllValuesInSheet (SpreadsheetDocument spreadSheet, string sheetName) { WorksheetPart worksheetPart = GetWorksheetPartByName(spreadSheet, sheetName); foreach (Row row in worksheetPart.Worksheet. GetFirstChild().Elements()) { foreach (Cell cell in row.Elements()) { if (cell.CellFormula != null && cell.CellValue != null) { cell.CellValue.Remove(); } } } worksheetPart.Worksheet.Save(); } Besides the fact that this snippet does not compile for me, it has two limitations: It only invalidates a single sheet, although other sheets might contain dependent formula It does not take into account any dependencies. I am looking for a way that is efficient (in particular, only invalidates cells that depend on a certain cell's value), and takes all sheets into account. Update: In the meantime I have managed to make the code compile & run, and to remove the cached values on all sheets of the workbook. (See answers.) Still I am interested in better/alternative solutions, in particular how to only delete cached values of the cells that actually depend on the updated cell.

    Read the article

  • T-SQL: Compute Subtotals For A Range Of Rows

    - by John Dibling
    MSSQL 2008. I am trying to construct a SQL statement which returns the total of column B for all rows where column A is between 2 known ranges. The range is a sliding window, and should be recomputed as it might be using a loop. Here is an example of what I'm trying to do, much simplified from my actual problem. Suppose I have this data: table: Test Year Sales ----------- ----------- 2000 200 2001 200 2002 200 2003 200 2004 200 2005 200 2006 200 2007 200 2008 200 2009 200 2010 200 2011 200 2012 200 2013 200 2014 200 2015 200 2016 200 2017 200 2018 200 2019 200 I want to construct a query which returns 1 row for every decade in the above table, like this: Desired Results: DecadeEnd TotalSales --------- ---------- 2009 2000 2010 2000 Where the first row is all the sales for the years 2000-2009, the second for years 2010-2019. The DecadeEnd is a sliding window that moves forward by a set ammount for each row in the result set. To illustrate, here is one way I can accomplish this using a loop: declare @startYear int set @startYear = (select top(1) [Year] from Test order by [Year] asc) declare @endYear int set @endYear = (select top(1) [Year] from Test order by [Year] desc) select @startYear, @endYear create table DecadeSummary (DecadeEnd int, TtlSales int) declare @i int -- first decade ends 9 years after the first data point set @i = (@startYear + 9) while @i <= @endYear begin declare @ttlSalesThisDecade int set @ttlSalesThisDecade = (select SUM(Sales) from Test where(Year <= @i and Year >= (@i-9))) insert into DecadeSummary values(@i, @ttlSalesThisDecade) set @i = (@i + 9) end select * from DecadeSummary This returns the data I want: DecadeEnd TtlSales ----------- ----------- 2009 2000 2018 2000 But it is very inefficient. How can I construct such a query?

    Read the article

< Previous Page | 155 156 157 158 159 160 161 162 163 164 165 166  | Next Page >