This driver was contributed by Microsoft and provides connections to SQL server databases greater than version 2000. It requires PHP version 5.3 or greater, Microsoft native client software and the appropriate PHP driver.

Sequences are supported in native mode in SQL Sever 2012, and emulated in earlier versions.

This driver was the primary connection method to SQL Server databases up to PHP Version 5.2.

This driver provides access to Microsoft SQL Server databases from unix systems via Freetds

This driver provides undocumented portability to the mssql driver

This driver appears to provide Unicode enhancements to the mssql driver