sql查询重复记录、删除重复记录方法

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前言:

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查找所有重复标题的记录:

SELECT *FROM t_info aWHERE ((SELECT COUNT(*)FROM t_infoWHERE Title = a.Title) > 1)ORDER BY Title DESC

一、查找重复记录

1.查找全部重复记录

Select * From 表 Where 重复字段 In (Select 重复字段 From 表 Group By 重复字段 Having Count(*)>1)

2.过滤重复记录(只显示一条)

Select * From HZT Where ID In (Select Max(ID) From HZT Group By Title)

注:此处显示ID最大一条记录

二、删除重复记录

1.删除全部重复记录(慎用)

Delete 表 Where 重复字段 In (Select 重复字段 From 表 Group By 重复字段 Having Count(*)>1)

2.保留一条记录

Delete HZT Where ID Not In (Select Max(ID) From HZT Group By Title)

注:此处保留ID最大一条记录

删除多余的重复记录

1.查找表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断

select * from peoplewhere peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)

2.删除表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断,只留有rowid最小的记录

delete from peoplewhere peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)and rowid not in (select min(rowid) from people group by peopleId having count(peopleId )>1)

3.查找表中多余的重复记录(多个字段)

select * from vitae awhere (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

4.删除表中多余的重复记录(多个字段),只留有rowid最小的记录

delete from vitae awhere (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)

5.查找表中多余的重复记录(多个字段),不包含rowid最小的记录

select * from vitae awhere (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)

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