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 ') group by categories_id' at line 1

select count(*) as number_in_category, categories_id from products p, products_to_categories p2c where p.products_id = p2c.products_id and p.products_fsk_18_hidden = '0' and p.products_status = '1' and p2c.categories_id in () group by categories_id