Mysql Update with table joins - 用其他表字段的总和更新一个表的字段

Question

我有两张桌子Orders 和Order_Details Order_Details 表的order_id 字段充当Orders 表的id_order 表的外键。

我想用来自Order_Details 表的价格总和来更新Orders 表的price_total 字段。

我尝试了以下查询但失败了：-

Update Orders, Order_Details
  SET  Orders.price_total = sum(Order_Details.price)
 WHERE Orders.price_total=0
 GROUP BY Order_Details.id_order

错误 -

#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 Order_Details.id_order' at line 4

如何在一个查询中完成？

谢谢

Answer 1

你可以把它简化成

Update Orders 
SET Orders.price_total = 
(
  SELECT 
    sum(Order_Details.price) 
  FROM Order_Details 
  WHERE 
    Orders.id_order=Order_Details.order_id
)
WHERE Orders.price_total=0;

更新分组

Update Orders, Order_Details
  SET Orders.price_total = sum(Order_Details.price)
WHERE 
  Orders.price_total=0 AND
  Orders.id_order=Order_Details.order_id    
GROUP BY Order_Details.id_order