什么意思。。。？
select mainId
from mainTable
where mainId in (
select mainId from relationTable, tagTable
where relationTable.tagId = tagTable.tagId )
如果要特定的某个（某些）tagId，就增加条件
select mainId
from mainTable
where mainId in (
select mainId from relationTable, tagTable
where relationTable.tagId = tagTable.tagId
and tagTable.tagId = ?? ) //--或者 tagTable.tagId in (……)
用union试下。
内容全部来源于网络收集，如有侵权，请联系网站删除：QQ：24596024