MSSQL PDO could not find driver

Not sure if this is due to running a CentOS x86_64 machine but sqlsrv didn't work as the driver for me, I had to use dblib:

try {

    $DBH = new PDO("dblib:host=xxxx;dbname=xxxx", 'xxxx', 'xxxx');

} catch (PDOException $e) {

    echo $e->getMessage();
}

Source and thanks to.

mssql is the old way of doing it, sqlsrv should be more appropriate! In fact the extension is called (extension=php_pdo_sqlsrv_53_ts_vc9.dll) as well ;)

try {

    $DBH = new PDO("sqlsrv:Server=xxxx;Database=xxxx", 'xxxx', 'xxxx');

} catch (PDOException $e) {

    echo $e->getMessage();
}

Hope this helps!

Source : http://php.net/manual/fr/ref.pdo-sqlsrv.connection.php