• 删除数据库重复数据的常用方法总结
  • 发布于 2个月前
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  • Carmelo
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背景:我们在做系统的时候,经常会遇到数据重复的问题,这个时候删除重复的数据就是我们必须要做的一件事情,那么在SQLSERVER中我们该如何删除重复的数据呢?今天我这就总结几条我们常见的几种删除数据库中重复数据的方法。

1、查找表中多余的重复记录,重复记录是根据单个字段(Id)来判断

select * fromwhere Id in (select Id fromgroup byId having count(Id) > 1)

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

DELETE fromWHERE (id) IN ( SELECT id FROMGROUP BY id HAVING COUNT(id) > 1) AND ROWID NOT IN (SELECT MIN(ROWID) FROMGROUP BY id HAVING COUNT(*) > 1);

3、查找表中多余的重复记录(多个字段)

select * from 表 a where (a.Id,a.seq) in(select Id,seq fromgroup by Id,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 表 a where (a.Id,a.seq) in (select Id,seq fromgroup by Id,seq having count(*) > 1) and rowid not in (select min(rowid) fromgroup by Id,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 表 a where (a.Id,a.seq) in (select Id,seq fromgroup by Id,seq having count(*) > 1) and rowid not in (select min(rowid) fromgroup by Id,seq having count(*)>1)

 

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