why it is not a defined MSSQL function??? mssql_select_db('[SwitchCenterDB]', $connect);

 in

PHP Fatal error: Call to undefined function mssql_select_db()

The source in question:

$connect = odbc_connect("DSNNAME", "miki", "84139") or die ("couldn't connect");
if ($connect) echo 'Great!';
else echo 'Damn';
mssql_select_db('[SwitchCenterDB]', $connect);