An Error Was Encountered

Error Number: 1054

Unknown column 'function.implode' in 'where clause'

SELECT MAX(`discount_amount`) AS da, `discount_type` FROM (`discount`) WHERE (0 >= discount_order_min) AND (0 >= discount_quantity_min) AND (cat_id=0 OR cat_id=0) AND (customer_id=0 OR customer_id=0) AND (product_id=function.implode OR product_id=0) AND (discount_product IN (0) OR discount_product=0) AND (discount_cat IN (0) OR discount_cat=0) AND (discount_code='' OR discount_code='') GROUP BY `product_id`, `customer_id`, `cat_id`, `discount_code`, `discount_order_min`, `discount_type`, `discount_product`, `discount_cat` ORDER BY `da` DESC