ive the answer to your question. Maybe someone will come in handy.
case ‘my_val’:
global $wpdb;
$my_cart = $wpdb->get_results(
”
SELECT user_id
FROM $wpdb->usermeta
WHERE meta_key = ‘my_cart’
AND meta_value = ‘$input_value’
”
);
if($my_cart) {
$output[‘error’] = __(‘this number is already.’,’userpro’);
}
break;