我在MySql中有三个表。表1具有以下字段
表格1:
EventType
-etid
-description
表2:
EventAsks
-etid
-qid
表3:
Questions
-qid
-textofquestion
如果我有一个特定的etid,并且想查找该事件要求的所有问题。因此,鉴于下表...
EventType
etid description
1 hiking
2 biking
EventAsks
etid qid
1 1
1 3
2 2
2 3
Questions
qid textofquestion
1 Is it fun?
2 Is it lots of exercise
3 Is it expensive
因此,给定的etid的结果为etid = 1,我希望返回与etid = 1相关的问题...
Result
Is it fun?
Is it expensive?
我确定这与联接有关,但是我不知道该怎么做?有什么建议么?
最佳答案
经典的N对N关系:
SELECT Questions.textofquestion FROM EventType
LEFT JOIN EventAsks ON EventAsks.etid = EventType.etid
LEFT JOIN Questions ON Questions.quid = EventAsks.qid
WHERE EventType.etid = 1;
关于mysql - INNER JOIN的SQL语法问题,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/15126098/