Question

这是我当前的查询：（它是一个触发器）

UPDATE qanda SET closed = COALESCE(closed, 0) + 1 WHERE id = new.qanda_id

现在我需要让它更先进。目前它总是增加+ 1。我想加入users表并检查这些：

如果role_id == 1则+ 5
如果reputation > 5000则+ 5

我该怎么做？

这就是我所做的。我想用CASE WHEN（如何？）

BEGIN

SELECT reputation, role_id INTO @reputation , @role_id FROM users WHERE id = new.user_id;

IF (@reputation >= 5000 OR role_id == 1) THEN
    UPDATE qanda SET closed = COALESCE(closed, 0) + 5 WHERE id = new.qanda_id;
ELSE
    UPDATE qanda SET closed = COALESCE(closed, 0) + 1 WHERE id = new.qanda_id;
END IF

END

Answer 1

update qanda q, users u 
set q.closed=COALESCE(q.closed, 0) + if((u.reputation >= 5000 OR u.role_id = 1),5,1)
where q.id = u.qanda_id

Answer 2

您可以使用单个UPDATE：

执行此操作

UPDATE qanda q JOIN
       users u
       ON q.id = new.qanda_id AND u.id = new.user_id
    SET q.closed = COALESCE(q.closed, 0) + 
                   (CASE WHEN u.reputation >= 5000 OR u.role_id = 1 THEN 5 ELSE 1 END);

如何为更新创建动态值？

2 个答案: