The connection string to use with PHP, dblib and SQL Server

If you are trying to connect to an SQL Server database with the dblib drivers for PDO, this is the correct connection string to use:

new PDO('dblib:host='.$host.';dbname='.$database, $this->user, $this->password);

You can also specify the encoding with charset=UTF-8 or charset=ISO-8859-1 if necessary.

Be aware that dblib is incredibly buggy and that it does not support unicode or transactions. I have also encountered important other bugs, such as being unable to use ERRMODE_EXCEPTION. However, there are not that many alternatives if you want have to connect to SQL Server from PHP on Linux