mysql根据条件使用一条语句更新多张​​表的多条记录

Question

我有一个 mysql 表来记录这样的两个人的比赛：

- gameid
- id1 // id of player 1
- id2 // id of player 2
- score1 // score of player 1
- score2 // score of player 2
- state // state of the games is initially 0, then the score updates are made and in order to prevent further updates the state must be updated to 1

我需要检查记录并根据分数更新另一个表“用户”。前任： 如果 score1 > score2 我需要更新 3 件事：

1- the state of the game // from 0 to 1
2- in table "users" add 1 point to the column score for the user with userid = id1
2- in table "users" subtract 1 point from the column score for the user with userid = id2

到目前为止，我可以更新 1 和 2，但我需要在一个命令中完成所有 3 个更新：

UPDATE dbo.games AS GA , dbo.users AS US 
SET GA.state = 1, US.score = US.score + 1
WHERE US.id = GA.id1 AND GA.state = 0 and GA.score1 > GA.score2

我可以将 +1 和 -1 命令分开，它可以正常工作。但是当命令运行时，两个用户的分数都应该更新。有人可以帮忙吗？

Answer 1

UPDATE dbo.games AS GA , dbo.users AS US     
SET GA.state = 1, (CASE WHEN US.id =GA.id1 THEN US.score = US.score + 1
 ELSE WHEN US.id=id2 THEN US.score =US.score-1 END)  
WHERE  GA.state = 0 and GA.score1 > GA.score2

此查询在 US.id=id1 时将分数增加 1，当 US.id =id2 时将分数减少 1

Answer 2

应该这样做：

update dbo.games as ga, dbo.users as us
set 
    ga.state = 1, 
    us1.score = us1.score + case 
        when 
            (ga.score1 > ga.score2 and us.id = ga1.id1)
            or (ga.score2 > ga.score1 and us.id = ga2.id2)
        then 1
        else -1
    end
where 
    ga.state = 0 
    and ga.score1 <> ga.score2
    and us.id in (ga.id1, ga.id2)

逻辑是在用户表中选择两行，然后做条件逻辑来决定是否添加或删除一个点。

注意：您没有说明要如何处理平局比赛 - 因此此查询明确忽略它们。