oracle 查询重复数据并且删除, 只保留一条数据

数据库操作中,经常会因为导数据造成数据重复,需要进行数据清理,去掉冗余的数据,只保留正确的数据

一:重复数据根据单个字段进行判断

1、首先,查询表中多余的数据,由关键字段(name)来查询。

select * from  表   where   重复列    in (select   重复列     from    表   group by   重复列名   having count(重复列)>1)

2、删除表中重复数据,重复数据是根据单个字段(Name)来判断,只留有rowid最小的记录

delete from    表     where    重复列  in 

(select  重复列   from   表    group by  重复列   having count(重复列) >1) 

and rowid not in (select min(rowid) from 表 group by    重复列  having count(重复列)>1)


二:重复数据根据多个字段进行判断

1、首先,查询表中重复数据,由关键字段(Name,UNIT_ID)来查询。

select * from OA_ADDRESS_BOOK book1 where (book1.name,book1.unit_id) in 
(select book2.name,book2.unit_id from OA_ADDRESS_BOOK book2 group by  book2.name,book2.unit_id  having count(*)>1)

2、删除表中重复数据,重复数据是根据多个字段(Name,UNIT_ID)来判断,只留有rowid最小的记录

delete from OA_ADDRESS_BOOK a where (a.Name,a.UNIT_ID) in 
(select Name,UNIT_ID from OA_ADDRESS_BOOK group by Name,UNIT_ID having count(*) > 1) 
and rowid not in (select min(rowid) from OA_ADDRESS_BOOK group by Name,UNIT_ID having count(*)>1)

3、查询表中重复数据,重复数据是根据多个字段(Name,UNIT_ID)来判断,不包含rowid最小的记录

select name,unit_id from OA_ADDRESS_BOOK a where (a.Name,a.UNIT_ID) in 
(select Name,UNIT_ID from OA_ADDRESS_BOOK group by Name,UNIT_ID having count(*) > 1) 
and rowid not in (select min(rowid) from OA_ADDRESS_BOOK group by Name,UNIT_ID having count(*)>1)


二:重复数据根据多个字段进行判断

1、首先,查询表中重复数据,由关键字段(Name,UNIT_ID)来查询。

select * from OA_ADDRESS_BOOK book1 where (book1.name,book1.unit_id) in 
(select book2.name,book2.unit_id from OA_ADDRESS_BOOK book2 group by  book2.name,book2.unit_id  having count(*)>1)

2、删除表中重复数据,重复数据是根据多个字段(Name,UNIT_ID)来判断,只留有rowid最小的记录

delete from OA_ADDRESS_BOOK a where (a.Name,a.UNIT_ID) in 
(select Name,UNIT_ID from OA_ADDRESS_BOOK group by Name,UNIT_ID having count(*) > 1) 
and rowid not in (select min(rowid) from OA_ADDRESS_BOOK group by Name,UNIT_ID having count(*)>1)

3、查询表中重复数据,重复数据是根据多个字段(Name,UNIT_ID)来判断,不包含rowid最小的记录

select name,unit_id from OA_ADDRESS_BOOK a where (a.Name,a.UNIT_ID) in 
(select Name,UNIT_ID from OA_ADDRESS_BOOK group by Name,UNIT_ID having count(*) > 1) 
and rowid not in (select min(rowid) from OA_ADDRESS_BOOK group by Name,UNIT_ID having count(*)>1)

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