From Joomla! Documentation
Joomla 2.5 and higher supports SQLServer. The prerequisites to install and configure SQLServer before installing Joomla on SQLServer database instead of the traditional MySQL. SQLServer Express is great alternative especially if any one wants to leverage the power of Microsoft software stack within Joomla.
Case 1: Joomla running on SQLServer database on single machine (Development purposes)
- Download SQLServer 2008 Express, SQLServer 2008 Standard/Enterprise editions (R2 or later)[DowpnloadSQLServer]
- Download PHP Drivers PHPDrivers
- System requirements
- Download SQLSRV20.EXE to a temporary directory
- Run SQLSRV20.EXE
- When prompted, enter the path to the PHP extensions directory
- If you are using some sort of LAMP stack like XAMPP
- Copy php_sqlsrv_52_ts_vc6.dll to php/ext folder
- Make an entry in php.ini as follows
- If you need PDO or vc9 versions - please copy the "ts" version appropriate for your needs.
- If you are using IIS with PHP engine installed via FAST-CGI - please make the appropriate changes in c:\Program Files\php\php.ini and copy the dll to c:\Program Files\php\ext folder
- Now - You can install Joomla 2.5 by selecting the SQLServer 2008 from the dropdown list in the step 4 of the installation.
- After installation is complete - continue navigation around the administrator/site.