将2列相加，更新查询

Question

UPDATE tbl_users 
   SET cash = SUM(cash + (SELECT reward FROM tbl_missions WHERE id = 1)) 
 WHERE id = 1 
 LIMIT 1

这是我的查询。它不起作用，我搜索网络时找不到任何东西。我该如何解决？

谢谢！

Answer 1

我假设你正在尝试进行更新加入：

UPDATE `tbl_users` u
JOIN   (SELECT   id, SUM(`reward`) AS reward_total
        FROM     `tbl_missions` m
        GROUP BY id) ON u.id = m.id
SET    `cash` = `cash` + m.reward_total 
WHERE  `id` = 1

Answer 2

那不就是：

UPDATE `tbl_users` 
SET `cash` = `cash` + (SELECT `reward` FROM `tbl_missions` WHERE `id` = 1)
WHERE `id` = 1 
LIMIT 1

...除非我在你的问题中遗漏了什么，否则我认为这就是你要找的东西。