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• A typical mysql query( how to use subquery column into main query)

  - by I Like PHP

  I HAVE TWO TABLES shown below table_joining id join_id(PK) transfer_id(FK) unit_id transfer_date joining_date 1 j_1 t_1 u_1 2010-06-05 2010-03-05 2 j_2 t_2 u_3 2010-05-10 2010-03-10 3 j_3 t_3 u_6 2010-04-10 2010-01-01 4 j_5 NULL u_3 NULL 2010-06-05 5 j_6 NULL u_4 NULL 2010-05-05 table_transfer id transfer_id(PK) pastUnitId futureUnitId effective_transfer_date 1 t_1 u_3 u_1 2010-06-05 2 t_2 u_6 u_1 2010-05-10 3 t_3 u_5 u_3 2010-04-10 now i want to know total employee detalis( using join_id) which are currently working on unit u_3 . means i want only join_id j_1 (has transfered but effective_transfer_date is future date, right now in u_3) j_2 ( tansfered and right now in `u_3` bcoz effective_transfer_date has been passed) j_6 ( right now in `u_3` and never transfered) what i need to take care of below steps( as far as i know ) <1> first need to check from table_joining whether transfer_id is NULL or not <2> if transfer_id= is NULL then see unit_id=u_3 where joining_date <=CURDATE() ( means that person already joined u_3) <3> if transfer_id is NOT NULL then go to table_transfer using transfer_id (foreign key reference) <4> now see the effective_transfer_date regrading that transfer_id whether effective_transfer_date<=CURDATE() <5> if transfer date has been passed(means transfer has been done) then return futureUnitID otherwise return pastUnitID i used two separate query but don't know how to join those query?? for step <1 ans <2 SELECT unit_id FROM table_joining WHERE joining_date<=CURDATE() AND transfer_id IS NULL AND unit_id='u_3' for step<5 SELECT IF(effective_transfer_date <= CURDATE(),futureUnitId,pastUnitId) AS currentUnitID FROM table_transfer // here how do we select only those rows which have currentUnitID='u_3' ?? please guide me the process?? i m just confused with JOINS. i think using LEFT JOIN can return the data i need, or if we use subquery value to main query? but i m not getting how to implement ...please help me. Thanks for helping me alwayz

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• Classify data (cell array) based on years in MATLAB

  - by user2991243

  Suppose that we have this cell array of data : a={43 432 2006; 254 12 2008; 65 35 2000; 64 34 2000; 23 23 2006; 64 2 2010; 32 5 2006; 22 2 2010} Last column of this cell array is years. I want classify data(rows) based on years like this : a_2006 = {43 432 2006; 32 5 2006; 32 5 2006} a_2008 = {254 12 2008}; a_2000 = {65 35 2000; 64 34 2000} a_2010 = {64 2 2010; 22 2 2010} I have different years in column three in every cell array (this cell array is a sample) so I want an automatic method to determine the years and classify them to a_yearA , a_yearB etc. or other naming that I can distinguish years and call data years easily. How can I do this? Thanks.da

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• Database doesn't update using TransactionScope

  - by Dissonant

  I have a client trying to communicate with a WCF service in a transactional manner. The client passes some data to the service and the service adds the data to its database accordingly. For some reason, the new data the service submits to its database isn't being persisted. When I have a look at the table data in the Server Explorer no new rows are added... Relevant code snippets are below: Client static void Main() { MyServiceClient client = new MyServiceClient(); Console.WriteLine("Please enter your name:"); string name = Console.ReadLine(); Console.WriteLine("Please enter the amount:"); int amount = int.Parse(Console.ReadLine()); using (TransactionScope transaction = new TransactionScope(TransactionScopeOption.Required)) { client.SubmitData(amount, name); transaction.Complete(); } client.Close(); } Service Note: I'm using Entity Framework to persist objects to the database. [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)] public void SubmitData(int amount, string name) { DatabaseEntities db = new DatabaseEntities(); Payment payment = new Payment(); payment.Amount = amount; payment.Name = name; db.AddToPayment(payment); //add to Payment table db.SaveChanges(); db.Dispose(); } I'm guessing it has something to do with the TransactionScope being used in the client. I've tried all combinations of db.SaveChanges() and db.AcceptAllChanges() as well, but the new payment data just doesn't get added to the database!

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• Replace some column values depending on a condition, MATLAB

  - by darkcminor

  I have a matrix like A= 4.0000 120.0000 92.0000 0 0 37.6000 0.1910 30.0000 10.0000 168.0000 74.0000 0 0 38.0000 0.5370 34.0000 10.0000 139.0000 80.0000 0 0 27.1000 1.4410 57.0000 1.0000 139.0000 60.0000 23.0000 846.0000 30.1000 0.3980 59.0000 5.0000 136.0000 72.0000 19.0000 175.0000 25.8000 0.5870 51.0000 7.0000 121.0000 0 0 0 30.0000 0.4840 32.0000 I want to replace the values of the first column that are greater than '5' to 0, also in the second column if the values are in range 121-130 replace them by 0, if they are in range 131-140 replece by 1, 141-150 by 2, 151-160 by 3... so the result matrix would be A= 4.0000 0.0000 92.0000 0 0 37.6000 0.1910 30.0000 0.0000 4.0000 74.0000 0 0 38.0000 0.5370 34.0000 0.0000 1.0000 80.0000 0 0 27.1000 1.4410 57.0000 1.0000 1.0000 60.0000 23.0000 846.0000 30.1000 0.3980 59.0000 5.0000 1.0000 72.0000 19.0000 175.0000 25.8000 0.5870 51.0000 0.0000 0.0000 0 0 0 30.0000 0.4840 32.0000 How to acomplish this? I was trying something like counter=1; for i = 1: rows if A(i,1) > 5 A(i ,1) = 0; end if A(i,2) > 120 && A(i,2) < 130 A(i ,2) = 0; end counter = counter+1; end Using a case could do the trick?

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• PHP classes totally forgotten something today - sorry

  - by russp

  Hi guys, really sorry about being "totally thick today" but I have forgotten how to do something simple - too much time not in php recently. Want to use the OS phpapi How do I print out the individual rows - see told you I was being thick today // The fields we will be fetching. if (isset($_GET['test']) && $_GET['test'] == 'plaxo') { // plaxo is a PortableContacts end-point so doesn't know about the OpenSocial specific fields $profile_fields = array(); } else { $profile_fields = array( 'aboutMe', 'displayName', 'bodyType', 'currentLocation', 'drinker', 'happiestWhen', 'lookingFor' ); } // The number of friends to fetch. $friend_count = 2; $batch = $osapi->newBatch(); // Fetch the current user. $self_request_params = array( 'userId' => $userId, // Person we are fetching. 'groupId' => '@self', // @self for one person. 'fields' => $profile_fields // Which profile fields to request. ); $batch->add($osapi->people->get($self_request_params), 'self'); // Fetch the friends of the user $friends_request_params = array( 'userId' => $userId, // Person whose friends we are fetching. 'groupId' => '@friends', // @friends for the Friends group. 'fields' => $profile_fields, // Which profile fields to request. 'count' => $friend_count // Max friends to fetch. ); $batch->add($osapi->people->get($friends_request_params), 'friends'); // Get supportedFields Request $batch->add($osapi->people->getSupportedFields(), 'supportedFields'); // Send the batch request. $result = $batch->execute(); Say I wanted to print out "aboutMe", whats the echo? cos echo $result['aboutMe'] doesn't work.

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• SQL wont work? It doesn't come up with errors either

  - by Stefan

  Hey there, I have php function which checks to see if variables are set and then adds them onto my sql query. However I am don't seem to be getting any results back!? $where_array = array(); if (array_key_exists("location", $_GET)) { $location = addslashes($_GET['location']); $where_array[] = "`mainID` = '".$location."'"; } if (array_key_exists("gender", $_GET)) { $gender = addslashes($_GET["gender"]); $where_array[] = "`gender` = '".$gender."'"; } if (array_key_exists("hair", $_GET)) { $hair = addslashes($_GET["hair"]); $where_array[] = "`hair` = '".$hair."'"; } if (array_key_exists("area", $_GET)) { $area = addslashes($_GET["area"]); $where_array[] = "`locationID` = '".$area."'"; } $where_expr = ''; if ($where_array) { $where_expr = "WHERE " . implode(" AND ", $where_array); } $sql = "SELECT `postID` FROM `posts` ". $where_expr; $dbi = new db(); $result = $dbi->query($sql); $r = mysql_fetch_row($result); I'm trying to call the data after in a list like so: $dbi = new db(); $offset = ($currentpage - 1) * $rowsperpage; // get the info from the db $sql .= " ORDER BY `time` DESC LIMIT $offset, $rowsperpage"; $result = $dbi->query($sql); // while there are rows to be fetched... while ($row = mysql_fetch_object($result)){ // echo data echo $row['text']; } // end while Anyone got any ideas why I am not retrieving any data? -Stefan

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• C# Dataset Dynamically Add DataColumn

  - by Wesley

  I am trying to add a extra column to a dataset after a query has completed. I have a database relationship of the following: Employees / \ Groups EmployeeGroups Empoyees holds all the data for that individual, I'll name the unique key the UserID. Groups holds all the groups that a employee can be a part of, i.e. Super User, Admin, User; etc. I will name the unique key GroupID EmployeeGroups holds all the associations of which groups each employee belongs too. (UserID | GroupID) What I am trying to accomplish is after querying for a all users I want to loop though each user and add what groups that user is a part of by adding a new column to the dataset named 'Groups' which is a string to insert the values of the next query to get all the groups that user is a part of. Then by user of databinding populate a listview with all employees and their group associations My code is as follows; Position 5 is the new column I am trying to add to the dataset. string theQuery = "select UserID, FirstName, LastName, EmployeeID, Active from Employees"; DataSet theEmployeeSet = itsDatabase.runQuery(theQuery); DataColumn theCol = new DataColumn("Groups", typeof(string)); theEmployeeSet.Tables[0].Columns.Add(theCol); foreach (DataRow theRow in theEmployeeSet.Tables[0].Rows) { theRow.ItemArray[5] = "1234"; } At the moment, the code will create the new column but when i assign the data to that column nothing will be assigned, what am I missing? If there is any further explination or information I can provide, please let me know. Thank you all

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• Focus CSS tag in Internet Explorer 8

  - by Sam

  This is driving me nuts. http://www.cssdrive.com/index.php/examples/exampleitem/focus_pseudo_class This is an example of using the hover pseudo-class. Works fine in Chrome and IE. When I save locally it works fine in Chrome but won't work in IE. What am I doing wrong!? <link rel="Stylesheet" href="style.css" /> <form> <p>1) Name:<br /> <input type="text" size="40"></p> <p>2) Email address:<br /> <input type="text" size="40"></p> <p>3) Comments:<br /> <textarea rows="5" name="comments" cols="45" wrap="virtual"></textarea></p> <p><input id="actualsubmit" type="submit" value="Submit"></p> </form> style.css: input:focus, textarea:focus{ background-color: lightyellow; }

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• Read/Write/Find/Replace huge csv file

  - by notapipe

  I have a huge (4,5 GB) csv file.. I need to perform basic cut and paste, replace operations for some columns.. the data is pretty well organized.. the only problem is I cannot play with it with Excel because of the size (2000 rows, 550000 columns). here is some part of the data: ID,Affection,Sex,DRB1_1,DRB1_2,SENum,SEStatus,AntiCCP,RFUW,rs3094315,rs12562034,rs3934834,rs9442372,rs3737728 D0024949,0,F,0101,0401,SS,yes,?,?,A_A,A_A,G_G,G_G D0024302,0,F,0101,7,SN,yes,?,?,A_A,G_G,A_G,?_? D0023151,0,F,0101,11,SN,yes,?,?,A_A,G_G,G_G,G_G I need to remove 4th, 5th, 6th, 7th, 8th and 9th columns; I need to find every _ character from column 10 onwards and replace it with a space ( ) character; I need to replace every ? with zero (0); I need to replace every comma with a tab; I need to remove first row (that has column names; I need to replace every 0 with 1, every 1 with 2 and every ? with 0 in 2nd column; I need to replace F with 2, M with 1 and ? with 0 in 3rd column; so that in the resulting file the output reads: D0024949 1 2 A A A A G G G G D0024302 1 2 A A G G A G 0 0 D0023151 1 2 A A G G G G G G (both input and output should read one line per row, ne extra blank row) Is there a memory efficient way of doing that with java(and I need a code to do that) or a usable tool for playing with this large data so that I can easily apply Excel functionality..

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• Error in connection in ruby.

  - by piemesons

  require 'rubygems' require 'mysql' db = Mysql.connect('localhost', 'root', '', 'mohit') //db.rb:4: undefined method `connect' for Mysql:Class (NoMethodError) //undefined method `real_connect' for Mysql:Class (NoMethodError) db.query("CREATE TABLE people ( id integer primary key, name varchar(50), age integer)") db.query("INSERT INTO people (name, age) VALUES('Chris', 25)") begin query = db.query('SELECT * FROM people') puts "There were #{query.num_rows} rows returned" query.each_hash do |h| puts h.inspect end rescue puts db.errno puts db.error end error i am geting is: undefined method `connect' for Mysql:Class (NoMethodError) OR undefined method `real_connect' for Mysql:Class (NoMethodError) EDIT return value of Mysql.methods ["private_class_method", "inspect", "name", "tap", "clone", "public_methods", "object_id", "__send__", "method_defined?", "instance_variable_defined?", "equal?", "freeze", "extend", "send", "const_defined?", "methods", "ancestors", "module_eval", "instance_method", "hash", "autoload?", "dup", "to_enum", "instance_methods", "public_method_defined?", "instance_variables", "class_variable_defined?", "eql?", "constants", "id", "instance_eval", "singleton_methods", "module_exec", "const_missing", "taint", "instance_variable_get", "frozen?", "enum_for", "private_method_defined?", "public_instance_methods", "display", "instance_of?", "superclass", "method", "to_a", "included_modules", "const_get", "instance_exec", "type", "<", "protected_methods", "<=>", "class_eval", "==", "class_variables", ">", "===", "instance_variable_set", "protected_instance_methods", "protected_method_defined?", "respond_to?", "kind_of?", ">=", "public_class_method", "to_s", "<=", "const_set", "allocate", "class", "new", "private_methods", "=~", "tainted?", "__id__", "class_exec", "autoload", "untaint", "nil?", "private_instance_methods", "include?", "is_a?"] return value of Mysql.methods(false) is []... blank array

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• Why is my django bulk database population so slow and frequently failing?

  - by bryn

  I decided I'd like to use django's model system rather than coding raw SQL to interface with my database, but I am having a problem that surely is avoidable. My models.py contains: class Student(models.Model): student_id = models.IntegerField(unique = True) form = models.CharField(max_length = 10) preferred = models.CharField(max_length = 70) surname = models.CharField(max_length = 70) and I'm populating it by looping through a list as follows: from models import Student for id, frm, pref, sname in large_list_of_data: s = Student(student_id = id, form = frm, preferred = pref, surname = sname) s.save() I don't really want to be saving this to the database each time but I don't know another way to get django to not forget about it (I'd rather add all the rows and then do a single commit). There are two problems with the code as it stands. It's slow -- about 20 students get updated each second. It doesn't even make it through large_list_of_data, instead throwing a DatabaseError saying "unable to open database file". (Possibly because I'm using sqlite3.) My question is: How can I stop these two things from happening? I'm guessing that the root of both problems is that I've got the s.save() but I don't see a way of easily batching the students up and then saving them in one commit to the database.

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• Subset and lagging list data structure R

  - by user1234440

  I have a list that is indexed like the following: >list.stuff [[1]] [[1]]$vector ... [[1]]$matrix .... [[1]]$vector [[2]] null [[3]] [[3]]$vector ... [[3]]$matrix .... [[3]]$vector . . . Each segment in the list is indexed according to another vector of indexes: >index.list 1, 3, 5, 10, 15 In list.stuff, only at each of the indexes 1,3,5,10,15 will there be 2 vectors and one matrix; everything else will be null like [[2]]. What I want to do is to lag like the lag.xts function so that whatever is stored in [[1]] will be pushed to [[3]] and the last one drops off. This also requires subsetting the list, if its possible. I was wondering if there exists some functions that handle list manipulation. My thinking is that for xts, a time series can be extracted based on an index you supply: xts.object[index,] #returns the rows 1,3,5,10,15 From here I can lag it with: lag.xts(xts.object[index,]) Any help would be appreciated thanks: EDIT: Here is a reproducible example: list.stuff<-list() vec<-c(1,2,3,4,5,6,7,8,9) vec2<-c(1,2,3,4,5,6,7,8,9) mat<-matrix(c(1,2,3,4,5,6,7,8),4,2) list.vec.mat<-list(vec=vec,mat=mat,vec2=vec2) ind<-c(2,4,6,8,10) for(i in ind){ list.stuff[[i]]<-list.vec.mat }

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• Entity Framework + MySQL - Why is the performance so terrible?

  - by Cyril Gupta

  When I decided to use an OR/M (Entity Framework for MySQL this time) for my new project I was hoping it would save me time, but I seem to have failed it (for the second time now). Take this simple SQL Query SELECT * FROM POST ORDER BY addedOn DESC LIMIT 0, 50 It executes and gives me results in less than a second as it should (the table has about 60,000 rows). Here's the equivalent LINQ To Entities query that I wrote for this var q = (from p in db.post orderby p.addedOn descending select p).Take(50); var q1 = q.ToList(); //This is where the query is fetched and timed out But this query never even executes it times out ALWAYS (without orderby it takes 5 seconds to run)! My timeout is set to 12 seconds so you can imagine it is taking much more than that. Why is this happening? Is there a way I can see what is the actual SQL Query that Entity Framework is sending to the db? Should I give up on EF+MySQL and move to standard SQL before I lose all eternity trying to make it work? I've recalibrated my indexes, tried eager loading (which actually makes it fail even without the orderby clause) Please help, I am about to give up OR/M for MySQL as a lost cause.

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• iphone - grouping UIImageViews x blocking elements

  - by Mike

  I have to rotate several UIImageViews around a specific center. To accomplish this I am using the famous trick of putting these views as subviews of a larger one and rotating that one. The problem is that these subviews have to detect touches, because each one has buttons on it. The hierarchy is like this LARGE_VIEW | |_____ imageView1 | |_________ button1 | |_________ button2 | |_________ button3 | |_____ imageView2 |_________ button4 |_________ button5 |_________ button6 etc So, to make buttons respond to tap, I had to make this; [LARGE_VIEW setUserInteractionEnabled:YES]; [imageView1 setUserInteractionEnabled:YES]; [imageView2 setUserInteractionEnabled:YES]; ImageView1 and 2 are two vertical rows of buttons on each side of the screen. The problem is that there's another view below LARGE_VIEW and this view is not receiving the taps, because LARGE_VIEW is intercepting them first. I don't need LARGE_VIEW to detect any taps except on the two areas where imageView 1 and 2 are. LARGE_VIEW must let pass taps on the area defined by this rect (52, 0, 768-2*52, 1024). ImageView1 and 2 have this size: 52 pixels wide and 1024 pixels high (iPad). ImageView1's rect is: (0, 0, 52, 1024) and ImageView2's rect is: (768-52, 0, 52, 1024) LARGE_VIEW must let pass taps on the area defined by this rect (52, 0, 768-2*52, 1024). How to solve that? I need LARGE_VIEW detect taps on each rect defined on my previous paragraph and pass these taps to its subviews and just let pass taps outside these rects to the app, so other views BELOW, can detect taps too. thanks.

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• Export large amount of data from Oracle 10G to SQL Server 2005

  - by uniball

  Dear all, I need to export 100 million data rows (avg row length ~ 100 bytes) from Oracle 10G database table into SQL server (over WAN/VLAN with 6MBits/sec capacity) on a regular basis. So far, these are the options that I have tried and a quick summary. Has anyone tried this before? Are there other better options? Which option would be the best in terms of performance and reliability? The time taken has been calculated using tests on smaller amounts of data and then extrapolating it to estimate the time required. Using data import wizard on the SQL server or SSIS packages to import the data. It will take around 150 hours to complete the task. Using Oracle batch job to spool data into a comma-delimited flat-file. Then using SSIS package to FTP this file to the SQL server and then load directly from the flat-file. The issue here is the size of the flat-file which is expected to run in GBs. Although this option is drastically different, I am even considering the option of using Linked Server to query the Oracle data directly at run-time to avoid bringing in data. Performance is a big problem and I have limited control over the Oracle database in terms of creating table indexes. Regards, Uniball

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• Presenting collection of structures of strings in grid or similar in WPF - Example? Ideas?

  - by Andrew

  Hi, I have a collection of structures. The structure is just some strings. Example public struct ReportLine { public string Name; public string Address; public string Phone; ...// about 10 other strings } I can't change this part. What I want to do is display it in a simple grid or simlar in WPF. My only requirements are: a) need column headers b) rows must alternate in color c) columns big enough to hold largest datum (which is not know until run time) Can someone point me to an example to get me started? Is the GridView the way to go? Or DataGrid? Or perhaps just the grid? I have the book Pro WPF in C# 2008 and it covers binding ListBox's to collections, but the collections always seem to be collections of one field (ex. a collection of 40 names). Here I have a collection (an array in fact) of a structure. How do I setup the databinding? As you can see, I'm new to this and probably would most benefit from a reference to an article. I've found articles covering collections of 1 field, but no examples covering binding to an array of structures. Also, my intitial research indicates c) can't be easily done, if you demand that the column is big enough for all the data in that column, not just the visible data. Thanks, dave

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• Django: DatabaseError column does not exist

  - by Rosarch

  I'm having a problem with Django 1.2.4. Here is a model: class Foo(models.Model): # ... ftw = models.CharField(blank=True) bar = models.ForeignKey(Bar) Right after flushing the database, I use the shell: Python 2.6.6 (r266:84292, Sep 15 2010, 15:52:39) [GCC 4.4.5] on linux2 Type "help", "copyright", "credits" or "license" for more information. (InteractiveConsole) >>> from apps.foo.models import Foo >>> Foo.objects.all() Traceback (most recent call last): File "<console>", line 1, in <module> File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 67, in __repr__ data = list(self[:REPR_OUTPUT_SIZE + 1]) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 82, in __len__ self._result_cache.extend(list(self._iter)) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 271, in iterator for row in compiler.results_iter(): File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/compiler.py", line 677, in results_iter for rows in self.execute_sql(MULTI): File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/compiler.py", line 732, in execute_sql cursor.execute(sql, params) File "/usr/local/lib/python2.6/dist-packages/django/db/backends/util.py", line 15, in execute return self.cursor.execute(sql, params) File "/usr/local/lib/python2.6/dist-packages/django/db/backends/postgresql_psycopg2/base.py", line 44, in execute return self.cursor.execute(query, args) DatabaseError: column foo_foo.bar_id does not exist LINE 1: ...t_omg", "foo_foo"."ftw", "foo_foo... What am I doing wrong here?

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• Need to find number of new unique ID numbers in a MySQL table

  - by Nicholas

  I have an iPhone app out there that "calls home" to my server every time a user uses it. On my server, I create a row in a MySQL table each time with the unique ID (similar to a serial number) aka UDID for the device, IP address, and other data. Table ClientLog columns: Time, UDID, etc, etc. What I'd like to know is the number of new devices (new unique UDIDs) on a given date. I.e. how many UDIDs were added to the table on a given date that don't appear before that date? Put plainly, this is the number of new users I gained that day. This is close, I think, but I'm not 100% there and not sure it's what I want... SELECT distinct UDID FROM ClientLog a WHERE NOT EXISTS ( SELECT * FROM ClientLog b WHERE a.UDID = b.UDID AND b.Time <= '2010-04-05 00:00:00' ) I think the number of rows returned is the new unique users after the given date, but I'm not sure. And I want to add to the statement to limit it to a date range (specify an upper bound as well).

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• Can you catch exceeded allocated memory error before it kills the script?

  - by kristovaher

  The thing is that I want to catch memory problems before they happen. I have a system that gets rows from database and casts the returned associative array to a variable, but I never know what the size of the database result is is or how much memory it will take once the database request is made. This means that my software can fail simply because memory is exceeded. But I want to avoid that somehow. One of the ways is to obviously make database requests that are smaller, but what if this is not possible or what if I do not know the size of data that is returned from database? Is it possible to 'catch' situations where memory use is exceeded in PHP? Something like this: $requestOk=memory_test(function(){ return doSomething(); }); if($requestOk){ // Memory seems fine // $requestOk now has the value from memory_test() function } else { // Function would have exceeded memory } I just find it problematic that my script can just die at any moment because of memory issues. From what I know, try-catch cannot be used here because it is a fatal error. Any help would be appreciated!

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• Combining two-part SQL query into one query

  - by user332523

  Hello, I have a SQL query that I'm currently solving by doing two queries. I am wondering if there is a way to do it in a single query that makes it more efficient. Consider two tables: Transaction_Entries table and Transactions, each one defined below: Transactions - id - reference_number (varchar) Transaction_Entries - id - account_id - transaction_id (references Transactions table) Notes: There are multiple transaction entries per transaction. Some transactions are related, and will have the same reference_number string. To get all transaction entries for Account X, then I would do SELECT E.*, T.reference_number FROM Transaction_Entries E JOIN Transactions T ON (E.transaction_id=T.id) where E.account_id = X The next part is the hard part. I want to find all related transactions, regardless of the account id. First I make a list of all the unique reference numbers I found in the previous result set. Then for each one, I can query all the transactions that have that reference number. Assume that I hold all the rows from the previous query in PreviousResultSet UniqueReferenceNumbers = GetUniqueReferenceNumbers(PreviousResultSet) // in Java foreach R in UniqueReferenceNumbers // in Java SELECT * FROM Transaction_Entries where transaction_id IN (SELECT * FROM Transactions WHERE reference_number=R Any suggestions how I can put this into a single efficient query?

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• Non standard interaction among two tables to avoid very large merge

  - by riko

  Suppose I have two tables A and B. Table A has a multi-level index (a, b) and one column (ts). b determines univocally ts. A = pd.DataFrame( [('a', 'x', 4), ('a', 'y', 6), ('a', 'z', 5), ('b', 'x', 4), ('b', 'z', 5), ('c', 'y', 6)], columns=['a', 'b', 'ts']).set_index(['a', 'b']) AA = A.reset_index() Table B is another one-column (ts) table with non-unique index (a). The ts's are sorted "inside" each group, i.e., B.ix[x] is sorted for each x. Moreover, there is always a value in B.ix[x] that is greater than or equal to the values in A. B = pd.DataFrame( dict(a=list('aaaaabbcccccc'), ts=[1, 2, 4, 5, 7, 7, 8, 1, 2, 4, 5, 8, 9])).set_index('a') The semantics in this is that B contains observations of occurrences of an event of type indicated by the index. I would like to find from B the timestamp of the first occurrence of each event type after the timestamp specified in A for each value of b. In other words, I would like to get a table with the same shape of A, that instead of ts contains the "minimum value occurring after ts" as specified by table B. So, my goal would be: C: ('a', 'x') 4 ('a', 'y') 7 ('a', 'z') 5 ('b', 'x') 7 ('b', 'z') 7 ('c', 'y') 8 I have some working code, but is terribly slow. C = AA.apply(lambda row: ( row[0], row[1], B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))), axis=1).set_index(['a', 'b']) Profiling shows the culprit is obviously B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))). However, standard solutions using merge/join would take too much RAM in the long run. Consider that now I have 1000 a's, assume constant the average number of b's per a (probably 100-200), and consider that the number of observations per a is probably in the order of 300. In production I will have 1000 more a's. 1,000,000 x 200 x 300 = 60,000,000,000 rows may be a bit too much to keep in RAM, especially considering that the data I need is perfectly described by a C like the one I discussed above. How would I improve the performance?

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• php and mysql site design question

  - by Jacksta

  I am trying to build a website with mysql and php. This is the first site I have attempted so I want to write a little plan and get some feedback. The site allows users to add some text in a text field as a “comment”. Once the comment has been entered into the site it is added to the database where it can be voted for by other users. When a new comment has been added to the database it needs to create a new page, e.g. www.xxxxx.com/commentname or www.xxxxxx.com/?id=99981. There will be a list of "Comments" in the database along with the number of votes for each comment. The home page will have two functions. 1) Allow users to add a "comment" 2) Display two tables, each with 20 rows containing most "popular comments" and "recent comments" Each comment will generate its one page where the comment will be displayed. Here users can read the comment and Vote for the comment if they wish. Please help me out by explaining how to do the following. -Generate a new page whenever a comment is added to the database -Add a vote to the vote count in the comment database. -Display the top 20 most popular comments as per number of votes.

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• Does a Postgresql dump create sequences that start with - or after - the last key?

  - by bennylope

  I recently created a SQL dump of a database behind a Django project, and after cleaning the SQL up a little bit was able to restore the DB and all of the data. The problem was the sequences were all mucked up. I tried adding a new user and generated the Python error IntegrityError: duplicate key violates unique constraint. Naturally I figured my SQL dump didn't restart the sequence. But it did: DROP SEQUENCE "auth_user_id_seq" CASCADE; CREATE SEQUENCE "auth_user_id_seq" INCREMENT 1 START 446 MAXVALUE 9223372036854775807 MINVALUE 1 CACHE 1; ALTER TABLE "auth_user_id_seq" OWNER TO "db_user"; I figured out that a repeated attempt at creating a user (or any new row in any table with existing data and such a sequence) allowed for successful object/row creation. That solved the pressing problem. But given that the last user ID in that table was 446 - the same start value in the sequence creation above - it looks like Postgresql was simply trying to start creating rows with that key. Does the SQL dump provide the wrong start key by 1? Or should I invoke some other command to start sequences after the given start ID? Keenly curious.

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• What is a good approach to preloading data?

  - by Bob Horn

  Are there best practices out there for loading data into a database, to be used with a new installation of an application? For example, for application foo to run, it needs some basic data before it can even be started. I've used a couple options in the past: TSQL for every row that needs to be preloaded: IF NOT EXISTS (SELECT * FROM Master.Site WHERE Name = @SiteName) INSERT INTO [Master].[Site] ([EnterpriseID], [Name], [LastModifiedTime], [LastModifiedUser]) VALUES (@EnterpriseId, @SiteName, GETDATE(), @LastModifiedUser) Another option is a spreadsheet. Each tab represents a table, and data is entered into the spreadsheet as we realize we need it. Then, a program can read this spreadsheet and populate the DB. There are complicating factors, including the relationships between tables. So, it's not as simple as loading tables by themselves. For example, if we create Security.Member rows, then we want to add those members to Security.Role, we need a way of maintaining that relationship. Another factor is that not all databases will be missing this data. Some locations will already have most of the data, and others (that may be new locations around the world), will start from scratch. Any ideas are appreciated.

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• How to traverse table in Jquery and add a class?

  - by SWL

  I have a simple table of two rows. The first column is required, but the others are not; however, I would like them to be required in pairs. So if the user enters a value for Quantity3, then Size3 should also now be required. As a fiddle: http://jsfiddle.net/NaRts/7/ <tr> <td><input name="qty1[492]" class="qty required" type="text"></td> <td><input name="qty2[492]" class="qty" type="text"></td> <td><input name="qty3[492]" class="qty" type="text"></td> </tr><tr> <td><input name="size1[492]" type="text" class="size required" ></td> <td><input name="size2[492]" type="text" class="size" ></td> <td><input name="size3[492]" type="text" class="size" ></td> </tr> And the simple jQuery I have is: $('.qty').keyup(function() { var s = $(this).attr('name'); // = qty3[418] var qtyID = s.replace(/[^1-9\[\]]/g, ""); // = 3[418] var SizeID = "size" + qtyID; var $sizeInput = $(this).closest('tr').next().find(SizeID); $sizeInput.css('background-color', 'green'); $sizeInput.addClass('required'); //I tried this too but it didn't work //$(this).parent().find(SizeID).addClass('required'); });? ? Any help is much appreciated.

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