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Installing MSSQL for PHP

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This short manual is suitable if you are trying to run Moodle using the SQL*Server (MSSQL) RDBMS. Steps detailed below must be performed before installing Moodle itself.

Some of this may also apply if you wish to access an MSSQL server for external db authentication/enrollment.

First of all, minimum required version of MSSQL has been stabilised to MSSQL 2005 (v.9).

While PHP comes with one, more or less, standard extension (mssql) that provides access to MSSQL databases, early we found some hard limits on it. Basically such default extension has some limits that prevent us to use it at all (you can find more info about these problems here).

So, in order to allow PHP (i.e. Moodle) to access to MSSQL DBs properly we have to install a mssql extension alternative to save us from the problems related above. See the sections below for details about the various options.

Installation overview

1. Get MSSQL Server installed and running. (A free limited version, SQL Server Express Edition is available for testing.)

Make sure that you choose mixed authentication (Windows and local accounts) to keep things simpler later. You'll be asked to define the "sa" account password (it's the default System Administrator account which has full access to all databases by default).

2. Make sure MS SQL Server can accept incoming TCP/IP connections on port 1433 (the standard one).

You might need to explicitly allow this in your Windows firewall (see the Control Panel). You may also need to edit options in the :SQL Server Configuration Manager -> Network Configuration -> Protocols -> TCP/IP enabled

3. Open the "SQL Server Management Studio" and create a new empty database. If you are using the "sa" account then you don't need to do anything else here.

4. Configure these settings in your created (and still empty) database: Configure these settings in your created (and still empty) database:

  • Use a case sensitive collation, such as Latin1_General_CS_AS.
  • Quoted Identifiers Enabled = True (ALTER DATABASE xxxx SET QUOTED_IDENTIFIER ON)
  • Is Read Committed transaction ON = True (ALTER DATABASE xxxx SET READ_COMMITTED_SNAPSHOT ON)
    • In older versions this is not settable via the DB properties. To set READ_COMMITTED_SNAPSHOT, there must be no active connections to the database except for the connection executing the ALTER command. If you are viewing the DB in the Server Management Studio, disconnect from any servers in the "Object Explorer" (right-click > Disconnect), then create a "New Query" and run the ALTER command. See for details.
    • If your DB name starts with a number, you may need to put quotes around the DB name in the query.

5. Get PHP installed with a web server. Unless you want to do it under IIS or some other way, the packages on the Moodle download page are a good solution.

6. Choose one of the following specific sections for your server to install the mssql extension alternative installed and running properly on your PHP box.

7. Set the following settings in your php.ini file

  • mssql.textlimit = 20971520
  • mssql.textsize = 20971520

8. With all this properly configured, you can continue with a standard Moodle installation.

Microsoft Drivers for SQL Server for PHP

In July 2008 Microsoft released a new SQL Server Driver for PHP. This is a PHP extension that allows PHP scripts to read and write data on Microsoft SQL Server databases and it overcomes the problems with the native SQL Server extension that was previously bundled with PHP.

When using IIS it is strongly recommended to use the official Microsoft PHP installer from, it should include the latest version of necessary drivers and it also simplifies future upgrades and configuration.

For Windows servers with Apache see

To know more about how to run Moodle with these drivers go to Using the Microsoft SQL Server Driver for PHP.

Using FreeTDS on Windows

Important Note 1: Due to some previous bugs it's highly recommendable to use PHP >= 5.2.6 and FreeTDS 0.82 + post-release patches (more info).

If your web server is on Windows, use php_dblib.dll. Despite the name, it's FreeTDS compiled for Windows. (Go to this page for information on Using FreeTDS for Unix.)

Originally we were using the DLLs available at Frank Kromann's site, but they are outdated (using old versions of FreeTDS) and that has caused some problems in the past.

So, right now, the recommended way to use FreeTDS under Windows is to use PHP 5.2.x following the following instructions:

1. Download the appropriate copy of php_dblib.dll from the list below, and save it into your /PHP/ext directory.

PHP version Thread Safe FreeTDS version Download URL
PHP 5.2.x (vc6) Yes 0.82 + 20090302 patches Download!
No 0.82 + 20090302 patches Download!
PHP 5.3.x (vc6) Yes 0.82 + 20090904 patches (unconfirmed) Download!
No 0.82 + 20090904 patches (unconfirmed) Download!
PHP 5.3.x (vc9) Yes 0.82 + 20090904 patches Download!
No 0.82 + 20090904 patches Download!
PHP 5.4.x (vc9) Yes 0.82 + 20110906 patches Download! Mirrors: 1 2 (ftp) 3
No 0.82 + 20110906 patches Download! Mirrors: 1 2 (ftp) 3
PHP 5.4.x (vc9) Yes 0.91.102 Download!
No 0.91.102 Download!
PHP 5.5.x (vc11-x86) Yes 0.91.89 Download!
No 0.91.89 Download!
PHP 5.5.x (vc11-x64) Yes 0.91.93 Download!
No 0.91.93 Download!
Thanks to Remote-Learner] (Moodle Partner) and specially to Bryan Williams, donating one Visual C++ 6.0 Pro license to Moodle. Thanks to Trevor Johnson and his builds of the dblib extensions. Thanks to Daniele, Doug, Luis, Sean and many others by their collaboration in MDL-14725. Thanks to Frediano Ziglio and James K. Lowden from by their support. Thanks to Alastair Hole and Matt Rusiniak for providing the PHP 5.3 builds of the libraries. Thanks to Enyby by providing the PHP 5.4 builds of the libraries. Thanks to David Aylmer and Matt Rusiniak for providing the PHP 5.5 builds of the libraries. Thanks!

(alternatively here you can find some instructions to build those freetds extensions under win32 yourself)

2. FreeTDS requires the .NET Framework v1.1 to be installed. You can download it from the Microsoft website along with its service pack. Alternatively, if you do not wish to install this framework, you can download the required DLL from Frank's site, and save it into your /PHP root directory.

3. Edit your /PHP/php.ini file and add this line:


Make sure that any lines referring to the php_mssql.dll extension are DISABLED (commented out).

4. When the PHP engine loads the FreeTDS extension it needs to be passed certain infiormation in order to be able to connect to your Moodle database. To retrieve this information FreeTDS looks for a file called freetds.conf in the root folder of the server that PHP installed on (e.g. C:\).

freetds.conf should have the following structure:

     host = (host name or ip of the MSSQL server)
     port = 1433
     client charset = UTF-8
     tds version = 8.0
     text size = 20971520

If you want to connect to a particular instance of MSSQL you should specify the instance name:

     host = (host name or ip of the MSSQL server)
     instance = xxx (instance name, e.g. INST2)
     port = 1433
     client charset = UTF-8
     tds version = 8.0
     text size = 20971520


  • You can configure FreeTDS to look for the freetds.conf file in any directory that you want - you don't have to use C:\. To do this create a SYSTEM environment variable called FREETDS and point it to the directory where you have installed the freetds.conf file. If you do not set this environment variable FreeTDS will look for the freetds.conf file in the C:\ folder, which is the default. One possible benefit of setting the FREETDS environment variable and using a different installation directory for freetds.conf is that C:\ is very predictable to a hacker that knows anything about FreeTDS and that is the first place that he would look if he wanted to compromise your system. So, using a different installation directory would just make your system stronger. See the FreeTDS Setting the environment variables documentation for more information about this FREETDS environment variable.
  • Alternatively, you can recompile the FreeTDS extension yourself and change the default location to your preferred location at compile time. Then it is not necessary to create any environment variable. You must just ensure that freetds.conf is in the same folder that you specify when you compile php_dblib.dll.
  • MSSQL is usually installed with port 1433 as the default. However, if the port was changed on your server when you installed MSSQL then you need to specify the correct port number.

5. Your Moodle config.php should include lines like these:

$CFG->dbtype = 'mssql'; // Required $CFG->dbhost = 'localhost'; // assuming MS SQL is on the same server, otherwise use an IP $CFG->dbname = 'moodle'; // or whatever you called the database you created $CFG->dbuser = 'yourusername'; // I usually use the 'sa' account (dbowner perms are enough) $CFG->dbpass = 'yourpassword'; $CFG->dbpersist = false; $CFG->prefix = 'mdl_'; //Prefix, you can change it, but NEVER leave it blank.

If you don't have a config.php file yet, it can be generated as normal from the Moodle installer. Alternatively you can use the config-dist.php file that comes with the Moodle package to create your own config.php file.

6. Restart or start your web server. If Moodle still cannot communicate with the database server, please turn display_startup_errors to "On" in your /PHP/php.ini file, then restart the web server and check for any errors that may indicate incorrect DLL versions or missing dependencies. These error reports, turned off by default in PHP, can be vital in locating a problem with new extension installations.

7. Database conection test, try this PHP script, just put in a text file called test.php change ('localhost', 'db_user', 'db_password') to suite your setup, and load from local host (http://localhost/test.php)...

<?php $link = mssql_connect('localhost', 'db_user', 'db_password'); if(!$link) { echo'Could not connect'; die('Could not connect: ' . mssql_error()); } echo'Successful connection'; mssql_close($link); ?>

8. Install Moodle as usual. Good luck!


If you encounter some problems you can try:

  • check that you have DotNet framework 1.1 installed (later version are installed on Vista, but you could need this specific one)
  • enable TCP/IP for MSSQL: SQL Server 2005 Network Configuration -> Protocols for MSSQLSERVER -> TCP/IP (Enable) -> Properties -> Ip Addresses -> (Active+Enable)
  • make sure the SQL Server Browser service is running SQL Server 2005 Network Configuration -> SQL Server Services
  • if you are using SQL Server 2005 and you have the error 4004: Unicode data in a Unicode-only collation or ntext data cannot be sent to clients using DB-Library (such as ISQL) or ODBC version 3.7 or earlier, try the ODBTP method (next chapter). The SQL Server complaining that it doesn't support pure Unicode via TDS or older versions of ODBC. Microsoft has deprecated DB-Library a long ago, in favor of ODBC, OLE DB, or SQL Native Client. Many new features of SQL 2005 aren't accessible via DB-Library so if you need them, you could have to switch away from tools based on TDS and DB-Library :(

FreeTDS on Linux (on Ubuntu by compiling an extension)

This is a good read to building a FreeTDS based mssql extension for apache on Ubuntu. Do note that freeTDS 0.91 was recently released, you can find latest versions here.

Note: the freetds.conf file you use should have "text size = 20971520" as mentioned in the FreeTDS on Windows section otherwise you might see sessions logging out or worse apache segmentation faults. Also see FreeTDS.

Note2: Please note that updating php tends to remove the freetds configurations. You might need to reconfigure freetds after an upgrade

Using FreeTDS on Debian Lenny

I found the following solution using:

  • PHP Version 5.2.6-1+lenny9
  • Microsoft SQL Server Enterprise Edition, version: 9.00.4053.00
apt-get install libsybdb5 freetds-common php5-sybase
/etc/init.d/apache2 restart

At the end of the process, if all goes fine, you will find in the mssql section of phpinfo();

MSSQL Support enabled
Library version FreeTDS

Once FreeTDS is correctly installed, don not forget to set it up following explanations in

See also