多字段查找和删除重复数据

嗯 多字段查找和删除重复数据。 in 语句在SQL Server 里面不能有多个字段的 所以用inner join 可以 0

select * from CET4Grade  a inner join

(select SJXQ,XQ,StudentID from dbo.CET4Grade

group by SJXQ,XQ,StudentID having count(*)>1)

b on a.SJXQ=b.SJXQ and a.XQ=b.XQ and a.StudentID=b.StudentID

删除 嗯 用exists

Delete t from dbo.CET4Grade t where exists

(

select SJXQ,XQ,StudentID from CET4Grade 

group by SJXQ,XQ,StudentID having count(*)>1 and SJXQ=t.SJXQ and XQ=t.XQ and StudentID=t.StudentID

)