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  • Does Python Django support custom SQL and denormalized databases with no Foreign Key relationships?

    - by Jay
    I've just started learning Python Django and have a lot of experience building high traffic websites using PHP and MySQL. What worries me so far is Python's overly optimistic approach that you will never need to write custom SQL and that it automatically creates all these Foreign Key relationships in your database. The one thing I've learned in the last few years of building Chess.com is that its impossible to NOT write custom SQL when you're dealing with something like MySQL that frequently needs to be told what indexes it should use (or avoid), and that Foreign Keys are a death sentence. Percona's strongest recommendation was for us to remove all FKs for optimal performance. Is there a way in Django to do this in the models file? create relationships without creating actual DB FKs? Or is there a way to start at the database level, design/create my database, and then have Django reverse engineer the models file?

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  • Speed-up of readonly MyISAM table

    - by Ozzy
    We have a large MyISAM table that is used to archive old data. This archiving is performed every month, and except from these occasions data is never written to the table. Is there anyway to "tell" MySQL that this table is read-only, so that MySQL might optimize the performance of reads from this table? I've looked at the MEMORY storage engine, but the problem is that this table is so large that it would take a large portion of the servers memory, which I don't want. Hope my question is clear enough, I'm a novice when it comes to db administration so any input or suggestions are welcome.

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  • MEMORY(HEAP) vs. InnoDB in a Read and Write Envirnment

    - by Johannes
    I want to programm a real-time application using MySQL. It needs a small table (less than 10000 rows) that will be under heavy read (scan) and write (update and some insert/delete) load. I am really speaking of 10000 updates or selects per second. These statements will be executed on only a few (less than 10) open mysql connections. The table is small and does not contain any data that needs to be stored on disk. So I ask which is faster: InnoDB or MEMORY (HEAP)? My thoughts are: Both enginges will probably serve SELECTs directly from memory, as even InnoDB will cache the whole table. What about the UPDATAEs? (innodb_flush_log_at_trx_commit?) My main concern is the locking behavior: InnoDB row lock vs. MEMORY table lock. Will this present the bottleneck in the MEMORY implementation? Thanks for your thoughts!

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  • get best streak with all details of each row

    - by Pritesh Gupta
    ID user_id win 1 1 1 2 1 1 3 1 0 4 1 1 5 2 1 6 2 0 7 2 0 8 2 1 9 1 0 10 1 1 11 1 1 12 1 1 13 1 1 14 3 1 I needs to get the complete row for the best streak. I am able to get best streak no. for each user using this post. get consecutive records in mysql Now, I needs to get each rows data for that are involved in the best streak. i.e. for user=1, I need the complete row data for id=10,11,12,13. i.e. user_id,win and id value for these best streak row using mysql. Kindly help me on this.

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  • configure apache with sql

    - by Chava
    Hello, I am newly using Apache Tomcat6.0 I am unable to access sql database through my jsp and getting java.lang.ClassNotFoundException: com.microsoft.jdbc.sqlserver.SQLServerDriver Tried steps at http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html downloaded drivers mysql-connector-java-5.1.9 and mysql-5.0.85-win32 na dkept in tomcat\lib modified web.xml with context details but this didinot help me. Please suggest and provide steps if possible. JSP code Driver d = (Driver)Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance(); Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver"); Connection con=DriverManager.getConnection("jdbc:microsoft:sqlserver://localhost:8080"); I am using sql server WampServer without a password and created databse and table successfully.

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  • mysqli prepare statment error?

    - by user310850
    Hi all, $mysqli = new mysqli("localhost", "root", "", "test"); $mysqli->query('PREPARE mid FROM "SELECT name FROM test_user WHERE id = ?"'); //$mysqli->query('PREPARE mid FROM "SELECT name FROM test_user" '); $res = $mysqli->query( 'EXECUTE mid 1;') or die(mysqli_error($mysqli)); while($resu = $res->fetch_object()) { echo '<br>' .$resu->name; } Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '1' at line 1 my php version is PHP Version 5.3.0 and mysql mysqlnd 5.0.5-dev - 081106 - $Revision: 1.3.2.27 $

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  • How can I clean up this SELECT query?

    - by Cruachan
    I'm running PHP 5 and MySQL 5 on a dedicated server (Ubuntu Server 8.10) with full root access. I'm cleaning up some LAMP code I've inherited and I've a large number of SQL selects with this type of construct: SELECT ... FROM table WHERE LCASE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE( strSomeField, ' ', '-'), ',', ''), '/', '-'), '&', ''), '+', '') ) = $somevalue Ignoring the fact that the database should never have been constructed to require such a select in the first place, and the $somevalue field will need to be parameterised to plug the gaping security hole, what is my best option for fixing the WHERE condition into something less offensive? If I was using MSSQL or Oracle I'd simply put together a user-defined function, but my experience with MySQL is more limited and I've not constructed a UDF with it before, although I'm happy coding C. Update: For all those who've already raised their eyebrows at this in the original code, $somevalue is actually something like $GET['product']—there are a few variations on the theme. In this case the select is pulling the product back from the database by product name—after stripping out characters so it matches what could be previously passed as a URI parameter.

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  • Mobile application using REST web services in java to access database

    - by user1761991
    HTML5+CSS+javascript mobile app need to communicate with mysql database through REST Web services.I have a doubt in how html5 app consuming web services(Both storing and retrieving data in mysql database). Moreover, the app is not a native one. Phonegap is used to built this app to support in all OS available. The required rest web sevices ought to have JAVA in server coding part.Is there any possibility of having generalized rest web services which can able to consumed from all OS? Can anyone suggest any ideas related to this ? As i am new to mobile development unable to figure out the right and correct method to proceed. Thanks in Advance

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  • How do I reload a Roo project without clearing the database?

    - by Omniwombat
    I've been learning how to build projects using Roo and am making good progress. I have the nucleus of a project which correctly displays my defined entities and allows me to create, edit, and delete the representative objects. I am using mysql at the database and I see that objects entered using the UI correctly appear in the mysql database. Per the Roo instructions, I am starting the webapp using "mvn tomcat:run". Unfortunately, I've discovered that whenever I restart Tomcat using Maven, it clears all of the existing objects out of the database. I'm left with empty tables. It seems to do this as the final step just prior to Tomcat stating that the server has started. I know this is just me being a n00b, but searches haven't been very helpful, none of the project's XML files seem relevant,

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  • How to use SOCI C++ Database library?

    - by NeDark
    I'm trying to implement soci in my program but I don't know how. I'm using C++ on linux, on a project on netbeans. I have followed the steps in http://soci.sourceforge.net/doc/structure.html to install it, and I tried to copy the files soci.h from /src/core and soci-mysql.h from /src/backends/mysql in my proyect but it gives compilation error (these files include other soci files, but it's illogical to copy all files into the directory...). I have read the guide several time but I don't understand what I'm doing wrong, the examples only include these files. Thanks. Edit: I have given more information in a comment below the answer. I don't know what steps I have to do to implement soci.

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  • Are there any frameworks for data subscription and update?

    - by Timothy Pratley
    There is one server with multiple clients. The clients are viewing subsets of the servers entire data. If the data that a client is viewing changes, the client should be informed of the changes so that it displays the current data. Example: Two clients are viewing a list of users in an administration screen. One client adds a new user to the list and modifies the permissions of another user. The other client sees the changes propagated to their view.

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  • Post and get at the same time in php

    - by user225269
    Do you have any suggestions with my problem. I need to use get and post at the same time. Get because I need to output what the user has typed. And post because I need to access the mysql database in relation to that input. It looks something like this: <form name="x" method="get" action="x.php"> <input name="year" type="text"> <select name="general" id="general"> <font size="3"> <option value="YEAR">Year</option> </form> This will output the contents of mysql depending on what the user will check: <form name="y" method="post" action"y.php"> <input name="fname" type="checkbox"> </form> And the form action of those two combined will look something like this: <?php if($_POST['general'] == 'YEAR'){ ?> <?php echo $_GET["year"]; ?> <?php $result2 = mysql_query("SELECT * FROM student WHERE student.YEAR='$syear'"); ?> <table border='1'> <tr> <?php if ( $ShowLastName ) { ?><th>LASTNAME</th><?php } ?> <?php if ( $ShowFirstName ) { ?><th>FIRSTNAME</th><?php } ?> </tr> <?php while ( $row = mysql_fetch_array($result2) ) { if (!$result2) { } ?> <tr> <td><?php echo $row['IDNO']?> </td> <td><?php echo $row['YEAR'] ?> </td> <?php if ( $ShowLastName ) { echo('<td>'.$row['LASTNAME'].'</td>'); } ?></td> <?php if ( $ShowFirstName ) { echo('<td>'.$row['FIRSTNAME'].'</td>'); } ?> I really get lots of undefined errors when I do this. What can you recommend that I should do in order to get the value inputted by the user together with the mysql data.

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  • How to recalculate primary index?

    - by JohnM2
    I have table in mysql database with autoincrement PRIMARY KEY. On regular basis rows in this table are being deleted an added. So the result is that value of PK of the latest row is growing very fast, but there is not so much rows in this table. What I want to do is to "recalculate" PK in this way, that the first row has PK = 1, second PK = 2 and so on. There are no external dependencies on PK of this table so it would be "safe". Is there anyway it can be done using only mysql queries/tools? Or I have to do it from my code?

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  • ODBC: when is the best time to create my database?

    - by mawg
    I have a windows program which generates PGP forms which will be filled in later. Those PHP forms will populate a database. It looks very much like MySql, but I can't be certain, so let's call it ODBC. And, yes, it does have to be a windows program. There will also be PHP forms which query the database - examine which tables and fields it contains and then generates forms which can be used to search the database (e.g, it finds a table with fields "employee_name", etc and generates a form which lets you search based on employee name. Let's call that design time and run time. At design time, some manager or IT guy or similar gets to define the nature of the database and at runtime 1) a worker fills in the form daily and 2) management can extract reports. Here's my question: given that the database is defined at "design time" (and populated at run time), where and how is best to do so? 1 I could use an ODBC interface from the windows program, but I am having difficulty finding something good to work with Delphi. Things like ADO and firebird tend to expect you to already have a database and allow you to manipulate it, but I can find no code example of how to create a database and some tables, so ... 2 I could used DOS commands from Delphi in my windows program. I just tried and got a response to MySql --version, but am not sure if MySql etc are more interactive. That is, can I use a script file or a very long stacked command with semicolons and returns separating? e.g 'CREATE DATABASE db; CREATE TABLE t1;' 3) Since the best way to work with databases seems to be PHP, perhaps my windows program could spit out a PHP page which would, when run in a browser, create the database. I have tried to make this as uncomplicated as I can, but please feel free to ask questions. It may be that there are several valid ways, but there is probably one 'better' solution in terms of ease of implementation or maintenance. Better scratch option 3. What if the user later wants to come back and have the windows program change the input form? It needs to update the database too.

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  • Bash init.d script detect that mysqld has started and is running

    - by Ricket
    I'm working on my dedicated server running CentOS. I found out that one of my applications which starts up via a script in /etc/init.d/ requires MySQL to be running, or else it throws an error, so essentially I currently have to start it by hand. How can I detect, in a bash script (#!/bin/sh), whether the MySQL service has started yet? Is there some way to poll port 3306 until it is open to accept connections, and only then continue with the script? Or maybe set an order so that the script doesn't run until the mysqld script runs?

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  • PreparedStatement throws MySQLSyntaxErrorException

    - by sqlBugs
    I have the following Java code: String query = "Select 1 from myTable where name = ? and age = ?"; PreparedStatement stmt = conn.prepareStatement(query); stmt.setString(1, name); stmt.setInt(2, age); ResultSet rs = stmt.executeQuery(); Whenever I run the above code, it throws an exception on line 2 (where the PreparedStatement is declared): Error 0221202: SQLException = com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '? AND age = ?' at line 1 Does anyone have any suggestions about what I am doing wrong? Thanks!

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  • 42000 Syntax error in query when executing prepared statement

    - by Griff McGriff
    I have been pulling my hair out trying to swap my current script over to PDO. I have simplified the MySQL query for this example, but the error remains even with this version. $sql = 'SELECT * FROM :table WHERE lastUpdate > :appDate'; try{ $db = connect(); $stmt = $db->prepare($sql); $stmt->bindParam(':table', $table); $stmt->bindParam(':appDate', $appDate); foreach($tablesToCheck as $table){ $stmt->execute(); $resultset[] = $stmt->fetchAll(); } } catch(PDOException $e){ print 'Error!: '.$e->getMessage().'<br/>'; }//End try catch $stmt-errorInfo() returns: ( [0] => 42000 [1] => 1064 [2] => You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''GroupName' WHERE lastUpdate > NULL' at line 1 )

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  • New replicaset resident memory is larger than the existing sets

    - by eded
    From the mongodb tutorial of how to resync a set, I wipe all the files in /data/db and restart the mongod process to resync the data. Everything looks ok, I get the same number of documents as the existing two sets(primary and one secondary). However, when I check the memory on MMS. it shows me my new resynced set/mongod process has a different memory status value than the other two. For existing twos using db.serverStatus.mem shows like the following: "mem" : { "bits" : 64, "resident" : 239, "virtual" : 66348, "supported" : true, "mapped" : 32865, "mappedWithJournal" : 65730 } however, the new resynced set shows like: "mem" : { "bits" : 64, "resident" : 1239, "virtual" : 52447, "supported" : true, "mapped" : 25700, "mappedWithJournal" : 51400 } the resynced resident memory is 6-10 times more than the existing ones. I wouder if it is normal because all data comes in suddenly during the resyncing?? and even virtual and mapped value are different too. Can anyone explain?? thanks

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  • Generating a set of files containing dumps of individual tables in a way that guarantees database co

    - by intuited
    I'd like to dump a MySQL database in such a way that a file is created for the definition of each table, and another file is created for the data in each table. I'd like this to be done in a way that guarantees database integrity by locking the entire database for the duration of the dump. What is the best way to do this? Similarly, what's the best way to lock the database while restoring a set of these dump files? edit I can't assume that mysql will have permission to write to files.

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  • What frameworks exist for data subscription and update?

    - by Timothy Pratley
    There is one server with multiple clients. The clients are viewing subsets of the servers entire data. If the data that a client is viewing changes, the client should be informed of the changes so that it displays the current data. Example: Two clients are viewing a list of users in an administration screen. One client adds a new user to the list and modifies the permissions of another user. The other client sees the changes propagated to their view. In the client side code I would like the users list to be updated by the framework itself, raising changed events such that it will be redrawn - similar to 'cells' or dataflow. I am looking specifically for a .NET or java implementation.

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  • how to handle db concurrency in client-server application in C#?

    - by RAJ K
    I am developing an application in C# WPF which will have Client-Server architecture (Client will do products sales billing). I am novice in this area and I asked this question to start my development process. Click here to view question. So, ultimately I have selected MySQl, WCf & WPF. Now I have one silly question. Do i need to handle DB concurrency explicitly in my application (like 3 clients inserting data same time) or MySQl will handle this without any conflict? To accomplish my project i thought, I will create a service in WCf which will do DB queries from client application. Do you have any suggestion to improve my application performance.

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