mysql的更新與表連接 - 更新一個表與其他表的字段

Question

的總和場我有兩個表Orders和Order_Details Order_Details表的order_id場作爲外鍵Orders表的id_order表。

我想更新price_total字段的Orders表格，其中表格的價格總和爲Order_Details。

我試着用下面的查詢，但失敗： -

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

錯誤 -

#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 

如何做一個查詢？

感謝

Answer 1

你可以把它簡化爲

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; 

更新進行分組

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