mysql 查询
有这样一个表
user_id(用户id)ques_id(问题id)their_answer(他们的回答)my_answer(我的回答)
要实现的是 用户的id和所有的id进行比较 查找回答的相同的题,并且查找出相同的题的我的回答和他们的回答,
求高手帮忙写出一个快速查询的sql语句,
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这个意思?
- SQL code
select a.user_id,a.my_answer from question a inner join (select ques_id from question where user_id=1 ) t on a.ques_id=t.ques_id
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自连接
select a.* from question a, question b where a.ques_id = b.ques_id and b.user_id=用户1的id
select a.* from question a, question b where a.ques_id = b.ques_id and b.user_id in (,用户1的id,用户2的id)
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带条件怎么会显示所有的id?
另外自连接要避免自己跟自己连接
select a.* from question a, question b where a.ques_id = b.ques_id and a.user_id b.user_id and b.user_id = '用户1的id'