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Oracle数据库如何查找删除重复的SQL语句

我要评论 2011/05/27 15:13:25 来源:绿色资源网 编辑:downcc.com [ ] 评论:0 点击:496次

查询及删除重复记录的SQL语句

  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)

  注:rowid为oracle自带不用该.....

  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)

  (二)

  比方说

  在A表中存在一个字段“name”,

  而且不同记录之间的“name”值有可能会相同,

  现在就是需要查询出在该表中的各记录之间,“name”值存在重复的项;

  Select Name,Count(*) From A Group By Name Having Count(*) > 1

  如果还查性别也相同大则如下:

  Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1

  (三)

  方法一

  declare @max integer,@id integer

  declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) >; 1

  open cur_rows

  fetch cur_rows into @id,@max

  while @@fetch_status=0

  begin

  select @max = @max -1

  set rowcount @max

  delete from 表名 where 主字段 = @id

  fetch cur_rows into @id,@max

  end

  close cur_rows

  set rowcount 0 方法二

  "重复记录"有两个意义上的重复记录,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)

  (四)

  查询重复

  select * from tablename where id in (

  select id from tablename

  group by id

  having count(id) > 1

  )

关键词:Oracle,数据库,SQL语句

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