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 '191'') limit 1' at line 5
in:
[select p2c.categories_id, p.master_categories_id from products p, products_to_categories p2c where p.products_id = '243' and p.products_id = p2c.products_id and (p.master_categories_id = '191'' or p2c.categories_id='191'') limit 1]