題解 | #返回產品名稱和每一項產品的總訂單數(shù)#
返回產品名稱和每一項產品的總訂單數(shù)
http://fangfengwang8.cn/practice/1c64fd9048364a58a8ffa541720359a4
select Products.prod_name, if(odIt.orders is NULl,0,odIt.orders) from Products left join (select prod_id,count(order_num) as orders from OrderItems group by prod_id) as odIt on Products.prod_id=odIt.prod_id order by Products.prod_name asc