Note: You are currently viewing documentation for Moodle 2.6. Up-to-date documentation for the latest stable version of Moodle may be available here: admin/environment/database/mssql.

admin/environment/database/mssql

From MoodleDocs

MS SQL 2005 or later is required for Moodle 2.3.

However, bear in mind that Mainstream Support from Microsoft for SQL Server 2005 ended on 12/04/2011, so you should not use SQL Server 2005 for new Moodle sites.