MySQL加入两个表并求和？

Question

我有2个表-orders和orderdetail。

我需要将它们结合在一起并显示总数。我可以加入他们，但如何计算总数？

SELECT * 
FROM Orders as o 
INNER JOIN OrderDetails as od on o.order_id = od.order_id 
WHERE o.table_id = 1

Answer 1

 select a.order_id,
 order_date,
 order_status,
 table_id,
 item_id,
 item_price,
 quantity,
 b.item_price*b.quantity as total
 from dbo.orders as a inner join dbo.orderdetails as b
 on a.order_id=b.order_id
 WHERE table_id = 1

  

更新：如您在注释中提到的，如果您想要一个自动将数量和item_price相乘的计算列，则需要   执行此查询：

  ALTER TABLE dbo.orderdetails ADD Total AS (quantity* item_price);