1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '1' or p2c.categories_id=''1') limit 1' at line 5
in:
[select p2c.categories_id, p.master_categories_id from znc_products p, znc_products_to_categories p2c where p.products_id = '12' and p.products_id = p2c.products_id and (p.master_categories_id = ''1' or p2c.categories_id=''1') limit 1]