With MySQLi, it looks like this: $mysqli = new mysqli($db_host, $db_user, $db_pass, $db_name); But, PDO is a bit different because it can interact 12 different types of databases: Oracle, PostgreSQL, SQLite, MySQL, Cubrid and several others. So, when using it you have to specify which driver you want to use. Like this: $conn = new PDO(“mysql:host={$db_host};dbname={$db_name}”, $db_user, $db_pass); Notice the “mysql:host=” bit. For different drivers, you just change out the “mysql” part. So, PostgreSQL would be: $conn = new PDO(“pgsql:host={$db_host};dbname={$db_name}”, $db_user, $db_pass); For Oracle, it’d be: $conn = new PDO(“oci:host={$db_host};dbname={$db_name}”, $db_user, $db_pass); And, so on. Nice thing is… The code