Fatal error: Uncaught TypeError: mysql_select_db(): Argument #2 ($link_identifier) must be of type resource, mysqli given in /home/certificadodigitaldf/www/checkout/index.php:43 Stack trace: #0 /home/certificadodigitaldf/www/checkout/index.php(43): mysql_select_db('certificadodig0...', Object(mysqli)) #1 {main} thrown in /home/certificadodigitaldf/www/checkout/index.php on line 43