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  • 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 OA_ADDRESS_BOOK where name in (select name from OA_ADDRESS_BOOK group by name having count(name)>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 OA_ADDRESS_BOOK where (Name) in 

    (select Name from OA_ADDRESS_BOOK group by Name having count(Name) >1) 

    and rowid not in (select min(rowid) from OA_ADDRESS_BOOK group by Name having count(Name)>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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  • 原文地址:https://www.cnblogs.com/soundcode/p/9054641.html
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