Oracle 关于去重的就几个方法

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Oracle查询重复数据并删除，只保留一条记录

 

操作步骤
 

一、重复记录根据单个字段来判断
 

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

 

select * from table where FIELD_CODE in(select FIELD_CODE from table group by FIELD_CODE having count(FIELD_CODE) >1)

 

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

 

delete from table where (FIELD_CODE) in (select FIELD_CODE from table group by FIELD_CODE having count(FIELD_CODE) >1) and rowid not in (select min(rowid) from table group by FIELD_CODE having count(*)>1)

 

 

二、重复记录根据多个字段来判断
 

1、查找表中多余的重复记录（多个字段）

 

select * from table a where (a.FIELD_CODE,a.DTA_ITEM_NAME) in(select FIELD_CODE,DTA_ITEM_NAME from table group by FIELD_CODE,DTA_ITEM_NAME having count(*) > 1)

 

 

2、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 table a where (a.FIELD_CODE,a.DTA_ITEM_NAME) in (select FIELD_CODE,DTA_ITEM_NAME from table group by FIELD_CODE,DTA_ITEM_NAME having count(*) > 1) and rowid not in (select min(rowid) from table group by FIELD_CODE,DTA_ITEM_NAME having count(*)>1)

 

 

3、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 table a where (a.FIELD_CODE,a.DTA_ITEM_NAME) in (select FIELD_CODE,DTA_ITEM_NAME from table group by FIELD_CODE,DTA_ITEM_NAME having count(*) > 1) and rowid not in (select min(rowid) from table group by FIELD_CODE,DTA_ITEM_NAME having count(*)>1)