สินค้าตัวไหนถูกสั่งบ่อยที่สุด?ไม่จำเป็นต้องใช้ทุกโต๊ะ
Which product has been ordered most number of times?It is not neccessary to use all the tables.
 products:  (product_details [ VARCHAR ] product_id [ VARCHAR) ]
SELECT t2.product_details FROM order_items AS t1 JOIN products AS t2 ON t1.product_id = t2.product_id GROUP BY t1.product_id ORDER BY COUNT(*) DESC LIMIT 1