A Database Error Occurred

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'or `category2_id` = or `category3_id` IS NULL ORDER BY `id` DESC' at line 3

SELECT * FROM `product` WHERE `category_id` = or `category2_id` = or `category3_id` IS NULL ORDER BY `id` DESC

Filename: models/Productlist_Model.php

Line Number: 55