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  • postgres SQL - pg_class question

    - by Sachin Chourasiya
    PostgreSQL stores statistics about tables in the system table called pg_class. The query planner accesses this table for every query. These statistics may only be updated using the analyze command. If the analyze command is not run often, the statistics in this table may not be accurate and the query planner may make poor decisions which can degrade system performance. Another strategy is for the query planner to generate these statistics for each query (including selects, inserts, updates, and deletes). This approach would allow the query planner to have the most up-to-date statistics possible. Why postgres always rely on pg_class instead?

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  • Is this a valid benefit of using embedded SQL over stored procedures?

    - by George
    Here's an argument for SPs that I haven't heard. Flamers, be gentle with the down tick, Since there is overhead associated with each trip to the database server, I would suggest that a POSSIBLE reason for placing your SQL in SPs over embedded code is that you are more insulated to change without taking a performance hit. For example. Let's say you need to perform Query A that returns a scalar integer. Then, later, the requirements change and you decide that it the results of the scalar is x that then, and only then, you need to perform another query. If you performed the first query in a SP, you could easily check the result of the first query and conditionally execute the 2nd SQL in the same SP. How would you do this efficiently in embedded SQL w/o perform a separate query or an unnecessary query? Here's an example: --This SP may return 1 or two queries. SELECT @CustCount = COUNT(*) FROM CUSTOMER IF @CustCount 10 SELECT * FROM PRODUCT Can this/what is the best way to do this in embedded SQL?

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  • getting sql records

    - by droidus
    when i run this code, it returns the topic fine... $query = mysql_query("SELECT topic FROM question WHERE id = '$id'"); if(mysql_num_rows($query) > 0) { $row = mysql_fetch_array($query) or die(mysql_error()); $topic = $row['topic']; } but when I change it to this, it doesn't run at all. why is this happening? $query = mysql_query("SELECT topic, lock FROM question WHERE id = '$id'"); if(mysql_num_rows($query) > 0) { $row = mysql_fetch_array($query) or die(mysql_error()); $topic = $row['topic']; $lockedThread = $row['lock']; echo "here: " . $lockedThread; }

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  • Insert using strored procedure from nhibernate

    - by jcreddy
    Hi I am using the following code snippets to insert values using stored procedure. the code is executing successfully but no record is inserted in DB. Please suggest with simple example. **---- stored procedure--------** Create PROCEDURE [dbo].[SampleInsert] @id int, @name varchar(50) AS BEGIN insert into test (id, name) values (@id, @name); END **------.hbm file-------** <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <sql-query name="Procedure"> exec SampleInsert :Id,:Name </sql-query> </hibernate-mapping> **--------c# code to insert value using above sp------** ISessionFactory sessionFactory = new Configuration().Configure().BuildSessionFactory(); ISession session = sessionFactory.OpenSession(); IQuery query = session.GetNamedQuery("Procedure"); query.SetParameter("Id", "222"); query.SetParameter("Name", "testsp"); query.SetResultTransformer(new NHibernate.Transform.AliasToBeanConstructorResultTransformer(typeof(Procedure).GetConstructors()[0])); Regards Jcreddy

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  • 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 ?>

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  • How to run a set of SQL queries from a file, in PHP?

    - by Harish Kurup
    I have some set of SQL queries which is in a file(i.e query.sql), and i want to run those queries in files using PHP, the code that i have wrote is not working, //database config's... $file_name="query.sql"; $query==file($file_name); $array_length=count($query); for($i=0;$i<$array_length;$i++) { $data .= $query[$i]; } echo $data; mysql_query($data); it echos the SQL Query from the file but throws an error at mysql_query() function...

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  • output all data from db to a php page

    - by Sarit
    Hi, I'm a real beginner with PHP & mysql. Just for studying and for a simple example at school I would like to work this simple query and possibly output all the rows (or maybe even one) to a very basic output on a php page: <?php $user= "root"; $host="localhost"; $password=""; $database = "PetCatalog"; $cxn = mysqli_connect($host,$user,$password,$database) or die ("couldn’t connect to server"); $query = "SELECT * FROM Pet"; $result = mysql_query($cxn,$query) or die ("Couldn’t execute query."); $row = mysqli_fetch_assoc($result); echo "$result"; ?> this is the error message i've been getting: Warning: mysql_query() expects parameter 1 to be string, object given in C:\xampplite\htdocs\myblog\query.php on line 18 Couldn’t execute query. What should I do? Thanks!

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  • nodejs, mongodb - How do I operate on data from multiple queries?

    - by Ryan
    Hi all, I'm new to JS in general, but I am trying to query some data from MongoDB. Basically, my first query retrieves information for the session with the specified session id. The second query does a simple geospacial query for documents with a location near the specified location. I'm using the mongodb-native javascript driver. All of these query methods return their results in callbacks, so they're non-blocking. This is the root of my troubles. What I'm needing to do is retrieve the results of the second query, and create an Array of sessionIds of all the returned documents. Then I'm going to pass those to a function later. But, I can't generate this array and use it anywhere outside the callback. Does anyone have any idea how to properly do this? http://dpaste.org/wXiE/

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  • PHP looping through an array to fetch a value for each key from database (third normal form)

    - by zomboble
    I am building a system, mostly for consolidating learning but will be used in practice. I will try and verbally explain the part of the E-R diagram I am focusing on: Each cadet can have many uniformID's Each Uniform ID is a new entry in table uniform, so cadets (table) may look like: id | name | ... | uniformID 1 | Example | ... | 1,2,3 uniform table: id | notes | cadet 1 | Need new blahh | 1 2 | Some stuff needed | 1 3 | Whatever you like | 1 On second thought, looks like I wont need that third column in the db. I am trying to iterate through each id in uniformID, code: <?php $cadet = $_GET['id']; // set from URL $query = mysql_query("SELECT `uniformID` FROM `cadets` WHERE id = '$cadet' LIMIT 1") or die(mysql_error()); // get uniform needed as string // store it while ($row = mysql_fetch_array($query)) { $uniformArray = $row['uniformID']; } echo $uniformArray . " "; $exploded = explode(",", $uniformArray); // convert into an array // for each key in the array perform a new query foreach ($exploded as $key => $value) { $query(count($exploded)); $query[$key] = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'"); } ? As I say, this is mainly for consolidation purposes but I have come up with a error, sql is saying: Fatal error: Function name must be a string in C:\wamp\www\intranet\uniform.php on line 82 line 82 is: $query[$key] = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'"); I wasn't sure it would work so I tried it and now i'm stuck! EDIT: Thanks to everyone who has contributed to this! This is now the working code: foreach ($exploded as $key => $value) { //$query(count($exploded)); $query = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'"); while ($row = mysql_fetch_array($query)) { echo "<tr> <td>" . $row['id'] . "</td> <td>" . $row['note'] . "</td> </tr>"; } } Added the while and did the iteration by nesting it in the foreach

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  • Insert using stored procedure from nhibernate

    - by jcreddy
    Hi I am using the following code snippets to insert values using stored procedure. the code is executing successfully but no record is inserted in DB. Please suggest with simple example. **---- stored procedure--------** Create PROCEDURE [dbo].[SampleInsert] @id int, @name varchar(50) AS BEGIN insert into test (id, name) values (@id, @name); END **------.hbm file-------** <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <sql-query name="Procedure"> exec SampleInsert :Id,:Name </sql-query> </hibernate-mapping> **--------c# code to insert value using above sp------** ISessionFactory sessionFactory = new Configuration().Configure().BuildSessionFactory(); ISession session = sessionFactory.OpenSession(); IQuery query = session.GetNamedQuery("Procedure"); query.SetParameter("Id", "222"); query.SetParameter("Name", "testsp"); query.SetResultTransformer(new NHibernate.Transform.AliasToBeanConstructorResultTransformer(typeof(Procedure).GetConstructors()[0])); Regards Jcreddy

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  • Logic - Time measurement

    - by user73384
    To measure the following for tasks- Last execution time and maximum execution time for each task. CPU load/time consumed by each task over a defined period informed by application at run time. Maximum CPU load consumed by each task. Tasks have following characteristics- First task runs as background – Event information for entering only Second task - periodic – Event information for entering and exiting from task Third task is interrupt , can start any time – no information available from this task Forth task highest priority interrupt , can start any time – Event information for entering and exiting from task Should use least possible execution time and memory. 32bit increment timer available for time counting. Lets prepare and discuss the logic, It’s OK to have limitations …! Questions on understanding problem statement are welcome

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  • Using cachedwithin attibute inside cfquery

    - by Jason
    When you use the cachedwithin attribute in a cfquery how does it store the query in memory. Does it store it by only the name you assign to the query? For example, if on my index page I cache a query for an hour and name it getPeople will a query with the same name on a different page (or the same page for that matter) use the cached results or does it use some better logic to decide if it is the same query? Also, if there is a variable in your query does the cache take into account the value of the variable?

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  • Beginner's Question about accessing mysql using OOP

    - by user345690
    I am reading the PHP and mySQL web development book and so far been doing all the PHP and mysql using procedural. But then it talks about accessing mysql with objects. This works for me: //I define $db so can connect $query="select * FROM testing"; $result=mysqli_query($db,$query); while($row=mysqli_fetch_array($result)){ //echo the data } But when I try to do it with classes, it doesn't $query="select * FROM testing"; $result=$db->query($query); $row=$result->fetch_assoc(); Do I have to write my own class so it defines what query and fetch_assoc does? Or what?

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  • converting ip to long string in mysql command !

    - by Mac Taylor
    hey guys I'm trying to use ip2country technique to show my users'flags simple thing to do is to write a sql statement and show users from session table and then query to see if their ip is in what range and show their flags it simple but dengerous becuase when showing 300 users online and fetching from session table and then query once again ip2country table to get the flags there will be surelly memory overusage problem now i wrote a query to make it in one query : SELECT s.session_ip,ipc.* FROM session s left join ip2country ipc ON ipc.ip_lo<=s.session_ip AND ipc.ip_hi>=s.session_ip WHERE s.session_time > '".( time() - 60) )."' now its clear above query is wrong cause ips saved in ip2country table is long string 1000013824 and ips saved in session table are real ip e.g. 193.169.0.0 now i know how to convert from ip to long in php ip2long() but is there any command in mysql to do it with out building another query !?

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  • Terminal echo issue

    - by user107602
    I've been using Ubuntu 10.04 LTS for a while, am quite new, using the terminal, made a script to open a project of mine containing multiple files with gedit - after execution of the respective script - gedit [filename1] [filename2] ... , terminal executes it successfully, gedit opens passed files and terminal is ready for another line. Well, today I came across a strange issue - after the execution of the above mentioned script, gedit initiates successfully, but terminal denies execution of commands and echoes all keyboard events, even specific ctrl+... functions - all until gedit is closed. I can't figure what caused this as my recent activity was focused around a C project, not regarding the terminal in any way. I recall being able to execute another line after initiating e.g. open gedit and compile a project within a single tab and session of a terminal window. Any help would be appreciated! Regards!

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  • files get uploaded just before they get cancelled

    - by user1763986
    Got a little situation here where I am trying to cancel a file's upload. What I have done is stated that if the user clicks on the "Cancel" button, then it will simply remove the iframe so that it does not go to the page where it uploads the files into the server and inserts data into the database. Now this works fine if the user clicks on the "Cancel" button in quickish time the problem I have realised though is that if the user clicks on the "Cancel" button very late, it sometimes doesn't remove the iframe in time meaning that the file has just been uploaded just before the user has clicked on the "Cancel" button. So my question is that is there a way that if the file does somehow get uploaded before the user clicks on the "Cancel" button, that it deletes the data in the database and removes the file from the server? Below is the image upload form: <form action="imageupload.php" method="post" enctype="multipart/form-data" target="upload_target_image" onsubmit="return imageClickHandler(this);" class="imageuploadform" > <p class="imagef1_upload_process" align="center"> Loading...<br/> <img src="Images/loader.gif" /> </p> <p class="imagef1_upload_form" align="center"> <br/> <span class="imagemsg"></span> <label>Image File: <input name="fileImage" type="file" class="fileImage" /></label><br/> <br/> <label class="imagelbl"><input type="submit" name="submitImageBtn" class="sbtnimage" value="Upload" /></label> </p> <p class="imagef1_cancel" align="center"> <input type="reset" name="imageCancel" class="imageCancel" value="Cancel" /> </p> <iframe class="upload_target_image" name="upload_target_image" src="#" style="width:0px;height:0px;border:0px;solid;#fff;"></iframe> </form> Below is the jquery function which controls the "Cancel" button: $(imageuploadform).find(".imageCancel").on("click", function(event) { $('.upload_target_image').get(0).contentwindow $("iframe[name='upload_target_image']").attr("src", "javascript:'<html></html>'"); return stopImageUpload(2); }); Below is the php code where it uploads the files and inserts the data into the database. The form above posts to this php page "imageupload.php": <body> <?php include('connect.php'); session_start(); $result = 0; //uploads file move_uploaded_file($_FILES["fileImage"]["tmp_name"], "ImageFiles/" . $_FILES["fileImage"]["name"]); $result = 1; //set up the INSERT SQL query command to insert the name of the image file into the "Image" Table $imagesql = "INSERT INTO Image (ImageFile) VALUES (?)"; //prepare the above SQL statement if (!$insert = $mysqli->prepare($imagesql)) { // Handle errors with prepare operation here } //bind the parameters (these are the values that will be inserted) $insert->bind_param("s",$img); //Assign the variable of the name of the file uploaded $img = 'ImageFiles/'.$_FILES['fileImage']['name']; //execute INSERT query $insert->execute(); if ($insert->errno) { // Handle query error here } //close INSERT query $insert->close(); //Retrieve the ImageId of the last uploded file $lastID = $mysqli->insert_id; //Insert into Image_Question Table (be using last retrieved Image id in order to do this) $imagequestionsql = "INSERT INTO Image_Question (ImageId, SessionId, QuestionId) VALUES (?, ?, ?)"; //prepare the above SQL statement if (!$insertimagequestion = $mysqli->prepare($imagequestionsql)) { // Handle errors with prepare operation here echo "Prepare statement err imagequestion"; } //Retrieve the question number $qnum = (int)$_POST['numimage']; //bind the parameters (these are the values that will be inserted) $insertimagequestion->bind_param("isi",$lastID, 'Exam', $qnum); //execute INSERT query $insertimagequestion->execute(); if ($insertimagequestion->errno) { // Handle query error here } //close INSERT query $insertimagequestion->close(); ?> <!--Javascript which will output the message depending on the status of the upload (successful, failed or cancelled)--> <script> window.top.stopImageUpload(<?php echo $result; ?>, '<?php echo $_FILES['fileImage']['name'] ?>'); </script> </body> UPDATE: Below is the php code "cancelimage.php" where I want to delete the cancelled file from the server and delete the record from the database. It is set up but not finished, can somebody finish it off so I can retrieve the name of the file and it's id using $_SESSION? <?php // connect to the database include('connect.php'); /* check connection */ if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); die(); } //remove file from server unlink("ImageFiles/...."); //need to retrieve file name here where the ... line is //DELETE query statement where it will delete cancelled file from both Image and Image Question Table $imagedeletesql = " DELETE img, img_q FROM Image AS img LEFT JOIN Image_Question AS img_q ON img_q.ImageId = img.ImageId WHERE img.ImageFile = ?"; //prepare delete query if (!$delete = $mysqli->prepare($imagedeletesql)) { // Handle errors with prepare operation here } //Dont pass data directly to bind_param store it in a variable $delete->bind_param("s",$img); //execute DELETE query $delete->execute(); if ($delete->errno) { // Handle query error here } //close query $delete->close(); ?> Can you please provide an sample code in your answer to make it easier for me. Thank you

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  • Empty database output in CI

    - by den-javamaniac
    Hi. I'm building a simple app and trying to test DB result output. But unfortunately all I'm getting is an array of size 0. Here's the controller code excerpt: $data['query'] = $this->db->query('SELECT role_id, role_privilege FROM role'); $this->load->view('welcome_message', $data); And a view code excerpt: <?php echo count($query->result_array())."<br/>"; foreach ($query->result() as $row){ echo $row->role_id . '<br/>'; echo $row->role_privilege . '<br/>'; } echo 'Total result '.$query->num_rows(); ?> And what I get is next: 0 Total result Running query from a command line gives a 2 rowed output. Can someone point out what i'm missing?

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  • How many results were returned?

    - by Pastor Bones
    I'm performing a query on a worksheet. I want to update the row if it exists or insert it if it doesn't. How can you check if a result was returned or not? $query = new Zend_Gdata_Spreadsheets_ListQuery(); $query->setSpreadsheetKey($this->currKey); $query->setWorksheetId($this->currWkshtId); $query->setSpreadsheetQuery('cid = ' . $data['cid']); $listFeed = $this->gdClient->getListFeed($query); // This does not work! if(empty($listFeed)){ echo 'No results found!'; }

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  • July, the 31 Days of SQL Server DMO’s – Day 19 (sys.dm_exec_query_stats)

    - by Tamarick Hill
    The sys.dm_exec_query_stats DMV is one of the most useful DMV’s out there when it comes to performance tuning. If you have been keeping up with this blog series this month, you know that I started out on Day 1 reviewing many of the DMV’s within the ‘exec’ namespace. I’m not sure how I missed this one considering how valuable it is, but hey, they say it’s better late than never right?? On Day 7 and Day 8 we reviewed the sys.dm_exec_procedure_stats and sys.dm_exec_trigger_stats respectively. This sys.dm_exec_query_stats DMV is very similar to these two. As a matter of fact, this DMV will return all of the information you saw in the other two DMV’s, but in addition to that, you can see stats for all queries that have cached execution plans on your server. You can even see stats for statements that are ran Ad-Hoc as long as they are still cached in the buffer pool. To better illustrate this DMV, let have a quick look at it: SELECT * FROM sys.dm_exec_query_stats As you can see, there is a lot of information returned from this DMV. I wont go into detail about each and every one of these columns, but I will touch on a few of them briefly. The first column is the ‘sql_handle’, which if you remember from Day 4 of our blog series, I explained how you can use this column to extract the actual SQL text that was executed. The next columns statement_start_offset and statement_end_offset provide you a way of extracting the exact SQL statement that was executed as part of a batch. The plan_handle column is used to extract the Execution plan that was used, which we talked about during Day 5 of this blog series. Later in the result set, you have columns to identify how many times a particular statement was executed, how much CPU time it used, how many reads/writes it performed, the duration, how many rows were returned, etc. These columns provide you with a solid avenue to begin your performance optimization. The last column I will touch on is the query_plan_hash column. A lot of times when you have Dynamic SQL running on your server, you have similar statements with different parameter values being passed in. Many times these types of statements will get similar execution plans and then a Binary hash value can be generated based on these similar plans. This query plan hash can be used to find the cost of all queries that have similar execution plans and then you can tune based on that plan to improve the performance of all of the individual queries. This is a very powerful way of identifying and tuning Ad-hoc statements that run on your server. As I stated earlier, this sys.dm_exec_query_stats DMV is a very powerful and recommended DMV for performance tuning. You are able to quickly identify statements that are running on your server and analyze their impact on system resources. Using this DMV to track down the biggest performance killers on your server will allow you to make the biggest gains once you focus your tuning efforts on those top offenders. For more information about this DMV, please see the below Books Online link: http://msdn.microsoft.com/en-us/library/ms189741.aspx Follow me on Twitter @PrimeTimeDBA

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  • Brainless Backups

    - by Jesse
    I’m a software developer by trade which means to my friends and family I’m just a “computer guy”. It’s assumed that I know everything about every facet of computing from removing spyware to replacing hardware. I also can do all of this blindly over the phone or after hearing a five to ten word description of the problem over dinner ;-) In my position as CIO of my friends and families I’ve been in the unfortunate position of trying to recover music, pictures, or documents off of failed hard drives on more than one occasion. It’s not a great situation for anyone, and it’s always at these times that the importance of backups becomes so clear. Several months back a friend of mine found himself in this situation. The hard drive on his 8 year old laptop failed and took a good number of his digital photos with it. I think most folks can deal with losing some of their music and even some of their documents, but it really stings to lose pictures of past events and loved ones. After ordering a new laptop, my friend went out and bought an external hard drive so that he could start keeping a backup of his data. As fate would have it, several months later the drive in his new laptop failed and he learned the hard way that simply buying the external hard drive isn’t enough… you actually have to copy your stuff over every once in awhile! The importance of backup and recovery plans is (hopefully) well known in IT organizations. Well executed backup plans are in place, and hopefully the backup and recovery process is tested regularly. When you’re talking about users at home, however, the need for these backups is often understood far too late. Most typical users can’t be expected to remember to backup their data regularly and also don’t always have the know-how to setup automated backups. For my friends and family members in this situation I recommend tools like Dropbox, Carbonite, and Mozy. Here’s why I like them: They’re affordable: Dropbox and Mozy both have free offerings, though most people with lots of music and/or photos to backup will probably exceed the storage limitations of those free plans pretty quickly. Still, all three offer pretty affordable monthly or yearly plans. In my opinion, Carbonite’s unlimited storage plan for $50-$60 per year is the best value around. They’re easy to setup: Both Dropbox and Carbonite are very easy to get setup and start using. I’ve never used Mozy, but I imagine it’s similarly painless to get up and running. Backups are automatically “off-site”: A backup that is sitting on an external hard drive right next to your computer is great, but might not protect against flood damage, a power surge, or other disasters in that single location. These services exist “in the cloud” so to speak, helping mitigate those concerns. Granted, this kind of backup scheme requires some trust in the 3rd party to protect your data from both malicious people and disastrous events. This truly is a bit of a double edged sword, but I sleep well at night knowing that my data is being backed up and secured by a company made up of engineers that focus on the business of doing backups right. Backups are “brainless”: What I like most about services like these is that they work “automagically” in the background, watching for files to be updated and automatically backing up those changes. There’s no need to remember to plug in that external drive and copy your data over. Since starting to recommend these services to my friends and family I find myself wearing my “data recovery” hat far less often. The only way backups are effective for your standard computer user is if they’re completely automatic. Backups need to be brainless, or they just won’t work.

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  • Parallelism in .NET – Part 10, Cancellation in PLINQ and the Parallel class

    - by Reed
    Many routines are parallelized because they are long running processes.  When writing an algorithm that will run for a long period of time, its typically a good practice to allow that routine to be cancelled.  I previously discussed terminating a parallel loop from within, but have not demonstrated how a routine can be cancelled from the caller’s perspective.  Cancellation in PLINQ and the Task Parallel Library is handled through a new, unified cooperative cancellation model introduced with .NET 4.0. Cancellation in .NET 4 is based around a new, lightweight struct called CancellationToken.  A CancellationToken is a small, thread-safe value type which is generated via a CancellationTokenSource.  There are many goals which led to this design.  For our purposes, we will focus on a couple of specific design decisions: Cancellation is cooperative.  A calling method can request a cancellation, but it’s up to the processing routine to terminate – it is not forced. Cancellation is consistent.  A single method call requests a cancellation on every copied CancellationToken in the routine. Let’s begin by looking at how we can cancel a PLINQ query.  Supposed we wanted to provide the option to cancel our query from Part 6: double min = collection .AsParallel() .Min(item => item.PerformComputation()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would rewrite this to allow for cancellation by adding a call to ParallelEnumerable.WithCancellation as follows: var cts = new CancellationTokenSource(); // Pass cts here to a routine that could, // in parallel, request a cancellation try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation()); } catch (OperationCanceledException e) { // Query was cancelled before it finished } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, if the user calls cts.Cancel() before the PLINQ query completes, the query will stop processing, and an OperationCanceledException will be raised.  Be aware, however, that cancellation will not be instantaneous.  When cts.Cancel() is called, the query will only stop after the current item.PerformComputation() elements all finish processing.  cts.Cancel() will prevent PLINQ from scheduling a new task for a new element, but will not stop items which are currently being processed.  This goes back to the first goal I mentioned – Cancellation is cooperative.  Here, we’re requesting the cancellation, but it’s up to PLINQ to terminate. If we wanted to allow cancellation to occur within our routine, we would need to change our routine to accept a CancellationToken, and modify it to handle this specific case: public void PerformComputation(CancellationToken token) { for (int i=0; i<this.iterations; ++i) { // Add a check to see if we've been canceled // If a cancel was requested, we'll throw here token.ThrowIfCancellationRequested(); // Do our processing now this.RunIteration(i); } } With this overload of PerformComputation, each internal iteration checks to see if a cancellation request was made, and will throw an OperationCanceledException at that point, instead of waiting until the method returns.  This is good, since it allows us, as developers, to plan for cancellation, and terminate our routine in a clean, safe state. This is handled by changing our PLINQ query to: try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation(cts.Token)); } catch (OperationCanceledException e) { // Query was cancelled before it finished } PLINQ is very good about handling this exception, as well.  There is a very good chance that multiple items will raise this exception, since the entire purpose of PLINQ is to have multiple items be processed concurrently.  PLINQ will take all of the OperationCanceledException instances raised within these methods, and merge them into a single OperationCanceledException in the call stack.  This is done internally because we added the call to ParallelEnumerable.WithCancellation. If, however, a different exception is raised by any of the elements, the OperationCanceledException as well as the other Exception will be merged into a single AggregateException. The Task Parallel Library uses the same cancellation model, as well.  Here, we supply our CancellationToken as part of the configuration.  The ParallelOptions class contains a property for the CancellationToken.  This allows us to cancel a Parallel.For or Parallel.ForEach routine in a very similar manner to our PLINQ query.  As an example, we could rewrite our Parallel.ForEach loop from Part 2 to support cancellation by changing it to: try { var cts = new CancellationTokenSource(); var options = new ParallelOptions() { CancellationToken = cts.Token }; Parallel.ForEach(customers, options, customer => { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // Check for cancellation here options.CancellationToken.ThrowIfCancellationRequested(); // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { theStore.EmailCustomer(customer); customer.LastEmailContact = DateTime.Now; } }); } catch (OperationCanceledException e) { // The loop was cancelled } Notice that here we use the same approach taken in PLINQ.  The Task Parallel Library will automatically handle our cancellation in the same manner as PLINQ, providing a clean, unified model for cancellation of any parallel routine.  The TPL performs the same aggregation of the cancellation exceptions as PLINQ, as well, which is why a single exception handler for OperationCanceledException will cleanly handle this scenario.  This works because we’re using the same CancellationToken provided in the ParallelOptions.  If a different exception was thrown by one thread, or a CancellationToken from a different CancellationTokenSource was used to raise our exception, we would instead receive all of our individual exceptions merged into one AggregateException.

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  • Integrate Bing Search API into ASP.Net application

    - by sreejukg
    Couple of months back, I wrote an article about how to integrate Bing Search engine (API 2.0) with ASP.Net website. You can refer the article here http://weblogs.asp.net/sreejukg/archive/2012/04/07/integrate-bing-api-for-search-inside-asp-net-web-application.aspx Things are changing rapidly in the tech world and Bing has also changed! The Bing Search API 2.0 will work until August 1, 2012, after that it will not return results. Shocked? Don’t worry the API has moved to Windows Azure market place and available for you to sign up and continue using it and there is a free version available based on your usage. In this article, I am going to explain how you can integrate the new Bing API that is available in the Windows Azure market place with your website. You can access the Windows Azure market place from the below link https://datamarket.azure.com/ There is lot of applications available for you to subscribe and use. Bing is one of them. You can find the new Bing Search API from the below link https://datamarket.azure.com/dataset/5BA839F1-12CE-4CCE-BF57-A49D98D29A44 To get access to Bing Search API, first you need to register an account with Windows Azure market place. Sign in to the Windows Azure market place site using your windows live account. Once you sign in with your windows live account, you need to register to Windows Azure Market place account. From the Windows Azure market place, you will see the sign in button it the top right of the page. Clicking on the sign in button will take you to the Windows live ID authentication page. You can enter a windows live ID here to login. Once logged in you will see the Registration page for the Windows Azure market place as follows. You can agree or disagree for the email address usage by Microsoft. I believe selecting the check box means you will get email about what is happening in Windows Azure market place. Click on continue button once you are done. In the next page, you should accept the terms of use, it is not optional, you must agree to terms and conditions. Scroll down to the page and select the I agree checkbox and click on Register Button. Now you are a registered member of Windows Azure market place. You can subscribe to data applications. In order to use BING API in your application, you must obtain your account Key, in the previous version of Bing you were required an API key, the current version uses Account Key instead. Once you logged in to the Windows Azure market place, you can see “My Account” in the top menu, from the Top menu; go to “My Account” Section. From the My Account section, you can manage your subscriptions and Account Keys. Account Keys will be used by your applications to access the subscriptions from the market place. Click on My Account link, you can see Account Keys in the left menu and then Add an account key or you can use the default Account key available. Creating account key is very simple process. Also you can remove the account keys you create if necessary. The next step is to subscribe to BING Search API. At this moment, Bing Offers 2 APIs for search. The available options are as follows. 1. Bing Search API - https://datamarket.azure.com/dataset/5ba839f1-12ce-4cce-bf57-a49d98d29a44 2. Bing Search API – Web Results only - https://datamarket.azure.com/dataset/8818f55e-2fe5-4ce3-a617-0b8ba8419f65 The difference is that the later will give you only web results where the other you can specify the source type such as image, video, web, news etc. Carefully choose the API based on your application requirements. In this article, I am going to use Web Results Only API, but the steps will be similar to both. Go to the API page https://datamarket.azure.com/dataset/8818f55e-2fe5-4ce3-a617-0b8ba8419f65, you can see the subscription options in the right side. And in the bottom of the page you can see the free option Since I am going to use the free options, just Click the Sign Up link for that. Just select I agree check box and click on the Sign Up button. You will get a recipt pagethat detail your subscription. Now you are ready Bing Search API – Web results. The next step is to integrate the API into your ASP.Net application. Now if you go to the Search API page (as well as in the Receipt page), you can see a .Net C# Class Library link, click on the link, you will get a code file named “BingSearchContainer.cs”. In the following sections I am going to demonstrate the use of Bing Search API from an ASP.Net application. Create an empty ASP.Net web application. In the solution explorer, the application will looks as follows. Now add the downloaded code file (“BingSearchContainer.cs”) to the project. Right click your project in solution explorer, Add -> existing item, then browse to the downloaded location, select the “BingSearchContainer.cs” file and add it to the project. To build the code file you need to add reference to the following library. System.Data.Services.Client You can find the library in the .Net tab, when you select Add -> Reference Try to build your project now; it should build without any errors. Add an ASP.Net page to the project. I have included a text box and a button, then a Grid View to the page. The idea is to Search the text entered and display the results in the gridview. The page will look in the Visual Studio Designer as follows. The markup of the page is as follows. In the button click event handler for the search button, I have used the following code. Now run your project and enter some text in the text box and click the Search button, you will see the results coming from Bing, cool. I entered the text “Microsoft” in the textbox and clicked on the button and I got the following results. Searching Specific Websites If you want to search a particular website, you pass the site url with site:<site url name> and if you have more sites, use pipe (|). e.g. The following search query site:microsoft.com | site:adobe.com design will search the word design and return the results from Microsoft.com and Adobe.com See the sample code that search only Microsoft.com for the text entered for the above sample. var webResults = bingContainer.Web("site:www.Microsoft.com " + txtSearch.Text, null, null, null, null, null, null); Paging the results returned by the API By default the BING API will return 100 results based on your query. The default code file that you downloaded from BING doesn’t include any option for this. You can modify the downloaded code to perform this paging. The BING API supports two parameters $top (for number of results to return) and $skip (for number of records to skip). So if you want 3rd page of results with page size = 10, you need to pass $top = 10 and $skip=20. Open the BingSearchContainer.cs in the editor. You can see the Web method in it as follows. public DataServiceQuery<WebResult> Web(String Query, String Market, String Adult, Double? Latitude, Double? Longitude, String WebFileType, String Options) {  In the method signature, I have added two more parameters public DataServiceQuery<WebResult> Web(String Query, String Market, String Adult, Double? Latitude, Double? Longitude, String WebFileType, String Options, int resultCount, int pageNo) { and in the method, you need to pass the parameters to the query variable. query = query.AddQueryOption("$top", resultCount); query = query.AddQueryOption("$skip", (pageNo -1)*resultCount); return query; Note that I didn’t perform any validation, but you need to check conditions such as resultCount and pageCount should be greater than or equal to 1. If the parameters are not valid, the Bing Search API will throw the error. The modified method is as follows. The changes are highlighted. Now see the following code in the SearchPage.aspx.cs file protected void btnSearch_Click(object sender, EventArgs e) {     var bingContainer = new Bing.BingSearchContainer(new Uri(https://api.datamarket.azure.com/Bing/SearchWeb/));     // replace this value with your account key     var accountKey = "your key";     // the next line configures the bingContainer to use your credentials.     bingContainer.Credentials = new NetworkCredential(accountKey, accountKey);     var webResults = bingContainer.Web("site:microsoft.com" +txtSearch.Text , null, null, null, null, null, null,3,2);     lstResults.DataSource = webResults;     lstResults.DataBind(); } The following code will return 3 results starting from second page (by skipping first 3 results). See the result page as follows. Bing provides complete integration to its offerings. When you develop search based applications, you can use the power of Bing to perform the search. Integrating Bing Search API to ASP.Net application is a simple process and without investing much time, you can develop a good search based application. Make sure you read the terms of use before designing the application and decide which API usage is suitable for you. Further readings BING API Migration Guide http://go.microsoft.com/fwlink/?LinkID=248077 Bing API FAQ http://go.microsoft.com/fwlink/?LinkID=252146 Bing API Schema Guide http://go.microsoft.com/fwlink/?LinkID=252151

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  • SmartAssembly Support: How to change the maps folder

    - by Bart Read
    If you've set up SmartAssembly to store error reports in a SQL Server database, you'll also have specified a folder for the map files that are used to de-obfuscate error reports (see Figure 1). Whilst you can change the database easily enough you can't change the map folder path via the UI - if you click on it, it'll just open the folder in Explorer - but never fear, you can change it manually and fortunately it's not that difficult. (If you want to get to these settings click the Tools > Options link on the left-hand side of the SmartAssembly main window.)   Figure 1. Error reports database settings in SmartAssembly. The folder path is actually stored in the database, so you just need to open up SQL Server Management Studio, connect to the SQL Server where your error reports database is stored, then open a new query on the SmartAssembly database by right-clicking on it in the Object Explorer, then clicking New Query (see figure 2).     Figure 2. Opening a new query against the SmartAssembly error reports database in SQL Server. Now execute the following SQL query in the new query window: SELECT * FROM dbo.Information You should find that you get a result set rather like that shown in figure 3. You can see that the map folder path is stored in the MapFolderNetworkPath column.   Figure 3. Contents of the dbo.Information table, showing the map folder path I set in SmartAssembly. All I need to do to change this is execute the following SQL: UPDATE dbo.Information SET MapFolderNetworkPath = '\\UNCPATHTONEWFOLDER' WHERE MapFolderNetworkPath = '\\dev-ltbart\SAMaps' This will change the map folder path to whatever I supply in the SET clause. Once you've done this, you can verify the change by executing the following again: SELECT * FROM dbo.Information You should find the result set contains the new path you've set.

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  • Basic Spatial Data with SQL Server and Entity Framework 5.0

    - by Rick Strahl
    In my most recent project we needed to do a bit of geo-spatial referencing. While spatial features have been in SQL Server for a while using those features inside of .NET applications hasn't been as straight forward as could be, because .NET natively doesn't support spatial types. There are workarounds for this with a few custom project like SharpMap or a hack using the Sql Server specific Geo types found in the Microsoft.SqlTypes assembly that ships with SQL server. While these approaches work for manipulating spatial data from .NET code, they didn't work with database access if you're using Entity Framework. Other ORM vendors have been rolling their own versions of spatial integration. In Entity Framework 5.0 running on .NET 4.5 the Microsoft ORM finally adds support for spatial types as well. In this post I'll describe basic geography features that deal with single location and distance calculations which is probably the most common usage scenario. SQL Server Transact-SQL Syntax for Spatial Data Before we look at how things work with Entity framework, lets take a look at how SQL Server allows you to use spatial data to get an understanding of the underlying semantics. The following SQL examples should work with SQL 2008 and forward. Let's start by creating a test table that includes a Geography field and also a pair of Long/Lat fields that demonstrate how you can work with the geography functions even if you don't have geography/geometry fields in the database. Here's the CREATE command:CREATE TABLE [dbo].[Geo]( [id] [int] IDENTITY(1,1) NOT NULL, [Location] [geography] NULL, [Long] [float] NOT NULL, [Lat] [float] NOT NULL ) Now using plain SQL you can insert data into the table using geography::STGeoFromText SQL CLR function:insert into Geo( Location , long, lat ) values ( geography::STGeomFromText ('POINT(-121.527200 45.712113)', 4326), -121.527200, 45.712113 ) insert into Geo( Location , long, lat ) values ( geography::STGeomFromText ('POINT(-121.517265 45.714240)', 4326), -121.517265, 45.714240 ) insert into Geo( Location , long, lat ) values ( geography::STGeomFromText ('POINT(-121.511536 45.714825)', 4326), -121.511536, 45.714825) The STGeomFromText function accepts a string that points to a geometric item (a point here but can also be a line or path or polygon and many others). You also need to provide an SRID (Spatial Reference System Identifier) which is an integer value that determines the rules for how geography/geometry values are calculated and returned. For mapping/distance functionality you typically want to use 4326 as this is the format used by most mapping software and geo-location libraries like Google and Bing. The spatial data in the Location field is stored in binary format which looks something like this: Once the location data is in the database you can query the data and do simple distance computations very easily. For example to calculate the distance of each of the values in the database to another spatial point is very easy to calculate. Distance calculations compare two points in space using a direct line calculation. For our example I'll compare a new point to all the points in the database. Using the Location field the SQL looks like this:-- create a source point DECLARE @s geography SET @s = geography:: STGeomFromText('POINT(-121.527200 45.712113)' , 4326); --- return the ids select ID, Location as Geo , Location .ToString() as Point , @s.STDistance( Location) as distance from Geo order by distance The code defines a new point which is the base point to compare each of the values to. You can also compare values from the database directly, but typically you'll want to match a location to another location and determine the difference for which you can use the geography::STDistance function. This query produces the following output: The STDistance function returns the straight line distance between the passed in point and the point in the database field. The result for SRID 4326 is always in meters. Notice that the first value passed was the same point so the difference is 0. The other two points are two points here in town in Hood River a little ways away - 808 and 1256 meters respectively. Notice also that you can order the result by the resulting distance, which effectively gives you results that are ordered radially out from closer to further away. This is great for searches of points of interest near a central location (YOU typically!). These geolocation functions are also available to you if you don't use the Geography/Geometry types, but plain float values. It's a little more work, as each point has to be created in the query using the string syntax, but the following code doesn't use a geography field but produces the same result as the previous query.--- using float fields select ID, geography::STGeomFromText ('POINT(' + STR (long, 15,7 ) + ' ' + Str(lat ,15, 7) + ')' , 4326), geography::STGeomFromText ('POINT(' + STR (long, 15,7 ) + ' ' + Str(lat ,15, 7) + ')' , 4326). ToString(), @s.STDistance( geography::STGeomFromText ('POINT(' + STR(long ,15, 7) + ' ' + Str(lat ,15, 7) + ')' , 4326)) as distance from geo order by distance Spatial Data in the Entity Framework Prior to Entity Framework 5.0 on .NET 4.5 consuming of the data above required using stored procedures or raw SQL commands to access the spatial data. In Entity Framework 5 however, Microsoft introduced the new DbGeometry and DbGeography types. These immutable location types provide a bunch of functionality for manipulating spatial points using geometry functions which in turn can be used to do common spatial queries like I described in the SQL syntax above. The DbGeography/DbGeometry types are immutable, meaning that you can't write to them once they've been created. They are a bit odd in that you need to use factory methods in order to instantiate them - they have no constructor() and you can't assign to properties like Latitude and Longitude. Creating a Model with Spatial Data Let's start by creating a simple Entity Framework model that includes a Location property of type DbGeography: public class GeoLocationContext : DbContext { public DbSet<GeoLocation> Locations { get; set; } } public class GeoLocation { public int Id { get; set; } public DbGeography Location { get; set; } public string Address { get; set; } } That's all there's to it. When you run this now against SQL Server, you get a Geography field for the Location property, which looks the same as the Location field in the SQL examples earlier. Adding Spatial Data to the Database Next let's add some data to the table that includes some latitude and longitude data. An easy way to find lat/long locations is to use Google Maps to pinpoint your location, then right click and click on What's Here. Click on the green marker to get the GPS coordinates. To add the actual geolocation data create an instance of the GeoLocation type and use the DbGeography.PointFromText() factory method to create a new point to assign to the Location property:[TestMethod] public void AddLocationsToDataBase() { var context = new GeoLocationContext(); // remove all context.Locations.ToList().ForEach( loc => context.Locations.Remove(loc)); context.SaveChanges(); var location = new GeoLocation() { // Create a point using native DbGeography Factory method Location = DbGeography.PointFromText( string.Format("POINT({0} {1})", -121.527200,45.712113) ,4326), Address = "301 15th Street, Hood River" }; context.Locations.Add(location); location = new GeoLocation() { Location = CreatePoint(45.714240, -121.517265), Address = "The Hatchery, Bingen" }; context.Locations.Add(location); location = new GeoLocation() { // Create a point using a helper function (lat/long) Location = CreatePoint(45.708457, -121.514432), Address = "Kaze Sushi, Hood River" }; context.Locations.Add(location); location = new GeoLocation() { Location = CreatePoint(45.722780, -120.209227), Address = "Arlington, OR" }; context.Locations.Add(location); context.SaveChanges(); } As promised, a DbGeography object has to be created with one of the static factory methods provided on the type as the Location.Longitude and Location.Latitude properties are read only. Here I'm using PointFromText() which uses a "Well Known Text" format to specify spatial data. In the first example I'm specifying to create a Point from a longitude and latitude value, using an SRID of 4326 (just like earlier in the SQL examples). You'll probably want to create a helper method to make the creation of Points easier to avoid that string format and instead just pass in a couple of double values. Here's my helper called CreatePoint that's used for all but the first point creation in the sample above:public static DbGeography CreatePoint(double latitude, double longitude) { var text = string.Format(CultureInfo.InvariantCulture.NumberFormat, "POINT({0} {1})", longitude, latitude); // 4326 is most common coordinate system used by GPS/Maps return DbGeography.PointFromText(text, 4326); } Using the helper the syntax becomes a bit cleaner, requiring only a latitude and longitude respectively. Note that my method intentionally swaps the parameters around because Latitude and Longitude is the common format I've seen with mapping libraries (especially Google Mapping/Geolocation APIs with their LatLng type). When the context is changed the data is written into the database using the SQL Geography type which looks the same as in the earlier SQL examples shown. Querying Once you have some location data in the database it's now super easy to query the data and find out the distance between locations. A common query is to ask for a number of locations that are near a fixed point - typically your current location and order it by distance. Using LINQ to Entities a query like this is easy to construct:[TestMethod] public void QueryLocationsTest() { var sourcePoint = CreatePoint(45.712113, -121.527200); var context = new GeoLocationContext(); // find any locations within 5 kilometers ordered by distance var matches = context.Locations .Where(loc => loc.Location.Distance(sourcePoint) < 5000) .OrderBy( loc=> loc.Location.Distance(sourcePoint) ) .Select( loc=> new { Address = loc.Address, Distance = loc.Location.Distance(sourcePoint) }); Assert.IsTrue(matches.Count() > 0); foreach (var location in matches) { Console.WriteLine("{0} ({1:n0} meters)", location.Address, location.Distance); } } This example produces: 301 15th Street, Hood River (0 meters)The Hatchery, Bingen (809 meters)Kaze Sushi, Hood River (1,074 meters)   The first point in the database is the same as my source point I'm comparing against so the distance is 0. The other two are within the 5 mile radius, while the Arlington location which is 65 miles or so out is not returned. The result is ordered by distance from closest to furthest away. In the code, I first create a source point that is the basis for comparison. The LINQ query then selects all locations that are within 5km of the source point using the Location.Distance() function, which takes a source point as a parameter. You can either use a pre-defined value as I'm doing here, or compare against another database DbGeography property (say when you have to points in the same database for things like routes). What's nice about this query syntax is that it's very clean and easy to read and understand. You can calculate the distance and also easily order by the distance to provide a result that shows locations from closest to furthest away which is a common scenario for any application that places a user in the context of several locations. It's now super easy to accomplish this. Meters vs. Miles As with the SQL Server functions, the Distance() method returns data in meters, so if you need to work with miles or feet you need to do some conversion. Here are a couple of helpers that might be useful (can be found in GeoUtils.cs of the sample project):/// <summary> /// Convert meters to miles /// </summary> /// <param name="meters"></param> /// <returns></returns> public static double MetersToMiles(double? meters) { if (meters == null) return 0F; return meters.Value * 0.000621371192; } /// <summary> /// Convert miles to meters /// </summary> /// <param name="miles"></param> /// <returns></returns> public static double MilesToMeters(double? miles) { if (miles == null) return 0; return miles.Value * 1609.344; } Using these two helpers you can query on miles like this:[TestMethod] public void QueryLocationsMilesTest() { var sourcePoint = CreatePoint(45.712113, -121.527200); var context = new GeoLocationContext(); // find any locations within 5 miles ordered by distance var fiveMiles = GeoUtils.MilesToMeters(5); var matches = context.Locations .Where(loc => loc.Location.Distance(sourcePoint) <= fiveMiles) .OrderBy(loc => loc.Location.Distance(sourcePoint)) .Select(loc => new { Address = loc.Address, Distance = loc.Location.Distance(sourcePoint) }); Assert.IsTrue(matches.Count() > 0); foreach (var location in matches) { Console.WriteLine("{0} ({1:n1} miles)", location.Address, GeoUtils.MetersToMiles(location.Distance)); } } which produces: 301 15th Street, Hood River (0.0 miles)The Hatchery, Bingen (0.5 miles)Kaze Sushi, Hood River (0.7 miles) Nice 'n simple. .NET 4.5 Only Note that DbGeography and DbGeometry are exclusive to Entity Framework 5.0 (not 4.4 which ships in the same NuGet package or installer) and requires .NET 4.5. That's because the new DbGeometry and DbGeography (and related) types are defined in the 4.5 version of System.Data.Entity which is a CLR assembly and is only updated by major versions of .NET. Why this decision was made to add these types to System.Data.Entity rather than to the frequently updated EntityFramework assembly that would have possibly made this work in .NET 4.0 is beyond me, especially given that there are no native .NET framework spatial types to begin with. I find it also odd that there is no native CLR spatial type. The DbGeography and DbGeometry types are specific to Entity Framework and live on those assemblies. They will also work for general purpose, non-database spatial data manipulation, but then you are forced into having a dependency on System.Data.Entity, which seems a bit silly. There's also a System.Spatial assembly that's apparently part of WCF Data Services which in turn don't work with Entity framework. Another example of multiple teams at Microsoft not communicating and implementing the same functionality (differently) in several different places. Perplexed as a I may be, for EF specific code the Entity framework specific types are easy to use and work well. Working with pre-.NET 4.5 Entity Framework and Spatial Data If you can't go to .NET 4.5 just yet you can also still use spatial features in Entity Framework, but it's a lot more work as you can't use the DbContext directly to manipulate the location data. You can still run raw SQL statements to write data into the database and retrieve results using the same TSQL syntax I showed earlier using Context.Database.ExecuteSqlCommand(). Here's code that you can use to add location data into the database:[TestMethod] public void RawSqlEfAddTest() { string sqlFormat = @"insert into GeoLocations( Location, Address) values ( geography::STGeomFromText('POINT({0} {1})', 4326),@p0 )"; var sql = string.Format(sqlFormat,-121.527200, 45.712113); Console.WriteLine(sql); var context = new GeoLocationContext(); Assert.IsTrue(context.Database.ExecuteSqlCommand(sql,"301 N. 15th Street") > 0); } Here I'm using the STGeomFromText() function to add the location data. Note that I'm using string.Format here, which usually would be a bad practice but is required here. I was unable to use ExecuteSqlCommand() and its named parameter syntax as the longitude and latitude parameters are embedded into a string. Rest assured it's required as the following does not work:string sqlFormat = @"insert into GeoLocations( Location, Address) values ( geography::STGeomFromText('POINT(@p0 @p1)', 4326),@p2 )";context.Database.ExecuteSqlCommand(sql, -121.527200, 45.712113, "301 N. 15th Street") Explicitly assigning the point value with string.format works however. There are a number of ways to query location data. You can't get the location data directly, but you can retrieve the point string (which can then be parsed to get Latitude and Longitude) and you can return calculated values like distance. Here's an example of how to retrieve some geo data into a resultset using EF's and SqlQuery method:[TestMethod] public void RawSqlEfQueryTest() { var sqlFormat = @" DECLARE @s geography SET @s = geography:: STGeomFromText('POINT({0} {1})' , 4326); SELECT Address, Location.ToString() as GeoString, @s.STDistance( Location) as Distance FROM GeoLocations ORDER BY Distance"; var sql = string.Format(sqlFormat, -121.527200, 45.712113); var context = new GeoLocationContext(); var locations = context.Database.SqlQuery<ResultData>(sql); Assert.IsTrue(locations.Count() > 0); foreach (var location in locations) { Console.WriteLine(location.Address + " " + location.GeoString + " " + location.Distance); } } public class ResultData { public string GeoString { get; set; } public double Distance { get; set; } public string Address { get; set; } } Hopefully you don't have to resort to this approach as it's fairly limited. Using the new DbGeography/DbGeometry types makes this sort of thing so much easier. When I had to use code like this before I typically ended up retrieving data pks only and then running another query with just the PKs to retrieve the actual underlying DbContext entities. This was very inefficient and tedious but it did work. Summary For the current project I'm working on we actually made the switch to .NET 4.5 purely for the spatial features in EF 5.0. This app heavily relies on spatial queries and it was worth taking a chance with pre-release code to get this ease of integration as opposed to manually falling back to stored procedures or raw SQL string queries to return spatial specific queries. Using native Entity Framework code makes life a lot easier than the alternatives. It might be a late addition to Entity Framework, but it sure makes location calculations and storage easy. Where do you want to go today? ;-) Resources Download Sample Project© Rick Strahl, West Wind Technologies, 2005-2012Posted in ADO.NET  Sql Server  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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