mysql四表联合查询怎么写限制条件

如果表结构都相同 select count(*) form (select * from (SELECT * FROM daban union SELECT * f FROM zhongban union SELECT * FROM xiaoban) where to_days(RegTime) = to_days(now()))

你的意思是说，只要表1的id在表2的uid中，就显示是把？下面这个sql可以

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select a.* from user a,userids b where position(concat(a.id) in b.ids)!=0

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