我需要在以下查询中,如果 Events.Type
字段等于 1,则带有 XXXXX 的查询部分应如下所示:
ON Stages.ID = Abandonments.IDstage
如果是 2,Events.Type 中带有 XXXXX 的查询部分如下所示:
ON Stages.ID > Abandonments.IDstage
查询
SELECT
*,
Events.Type
FROM Participants
INNER JOIN Times
ON Participants.ID = Times.IDparticipant
INNER JOIN Events
ON Events.ID = Participants.IDevent
AND Events.ID = Times.IDevent
INNER JOIN Stages
ON Events.ID = Stages.IDevent
AND Stages.ID = Times.IDstage
LEFT OUTER JOIN (SELECT
Retired.ID,
Retired.IDstage,
Retired.IDparticipant,
Retired.IDevent
FROM Retired) Abandonments
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
AND Participants.ID = Abandonments.IDparticipant
AND Events.ID = Abandonments.IDevent
WHERE Times.IDevent = 31
AND Times.IDstage = 156
ORDER BY Participants.ID
谢谢
最佳答案
您的 SQL 查询中有很多 X
,并且不显示您正在尝试构建的限定符,所以我不太知道您在这里试图达到的意图。
但是,您在问题中描述了解决方案。
因此:
ON ((Stages.ID = Abandonments.IDstage AND Events.Type = 1) OR
(Stages.ID > Abandonments.IDstage AND Events.Type = 2))
如果这些定义的参数都不为 true(例如 Events.Type = 3
),那么您需要添加限定符或 false 返回来排除整个 JOIN
ON ((Stages.ID = Abandonments.IDstage AND Events.Type = 1) OR
(Stages.ID > Abandonments.IDstage AND Events.Type = 2)) OR 2=1
关于mysql - 连接子查询时使用if条件,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/55731158/