数据库删除冗余数据（转载至网上）

操作的表名：R_RESOURCE_DETAILS

 

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