现在假设有一张学生住宿信息表，sql字段有 id（不是学号），房号，上次时间，本次时间，住宿名单1，住宿名单2，住宿名单3，住宿名单4， 要怎么通过这些字段找出是否有同名的学生。
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- SQL code
with cte as (select *, row_number() over( order by getdate()) as id from (select 住宿名单1 as col from tbunion allselect 住宿名单2 from tbunion allselect 住宿名单3 from tbunion allselect 住宿名单4 from tb) as t )select * from cte as a where exists ( select * from cte as b where a.col = b.col and a.id <> b.id)