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  • oracle查找重复记录-转

    SELECT *
    FROM t_info a
    WHERE ((SELECT COUNT(*)
              FROM t_info
              WHERE Title = a.Title) > 1)
    ORDER BY Title DESC

    一。查找重复记录

    1。查找全部重复记录

    Select * From 表 Where 重复字段 In (Select 重复字段 From 表 Group By 重复字段 Having Count(*)>1)

    2。过滤重复记录(只显示一条)

    Select * From HZT Where ID In (Select Max(ID) From HZT Group By Title)

    注:此处显示ID最大一条记录

    二。删除重复记录


    1。删除全部重复记录(慎用)

    Delete 表 Where 重复字段 In (Select 重复字段 From 表 Group By 重复字段 Having Count(*)>1)

    2。保留一条(这个应该是大多数人所需要的 ^_^)

    Delete HZT Where ID Not In (Select Max(ID) From HZT Group By Title)

    注:此处保留ID最大一条记录

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

    select * from people

    where peopleId in (select   peopleId from   people group by   peopleId having count(peopleId) > 1)

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

    delete from people

    where peopleId in (select   peopleId from people group by   peopleId   having count(peopleId) > 1)

    and rowid not in (select min(rowid) from   people group by peopleId having count(peopleId )>1)

    3、查找表中多余的重复记录(多个字段)

    select * from vitae a

    where (a.peopleId,a.seq) in   (select peopleId,seq from vitae group by peopleId,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 vitae a

    where (a.peopleId,a.seq) in   (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

    and rowid not in (select min(rowid) from vitae group by peopleId,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 vitae a

    where (a.peopleId,a.seq) in   (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

    and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)


    补充:

    有两个以上的重复记录,一是完全重复的记录,也即所有字段均重复的记录,二是部分关键字段重复的记录,比如Name字段重复,而其他字段不一定重复或都重复可以忽略。

    1、对于第一种重复,比较容易解决,使用

    select distinct * from tableName

    就可以得到无重复记录的结果集。

    如果该表需要删除重复的记录(重复记录保留1条),可以按以下方法删除

    select distinct * into #Tmp from tableName

    drop table tableName

    select * into tableName from #Tmp

    drop table #Tmp

    发生这种重复的原因是表设计不周产生的,增加唯一索引列即可解决。

    2、这类重复问题通常要求保留重复记录中的第一条记录,操作方法如下

    假设有重复的字段为Name,Address,要求得到这两个字段唯一的结果集

    select identity(int,1,1) as autoID, * into #Tmp from tableName

    select min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoID

    select * from #Tmp where autoID in(select autoID from #tmp2)

    最后一个select即得到了Name,Address不重复的结果集(但多了一个autoID字段,实际写时可以写在select子句中省去此列)

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  • 原文地址:https://www.cnblogs.com/zhangzhu/p/5454416.html
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