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Oracle查询删除表中重复记录

程序员文章站 2022-06-06 15:34:09
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最高效删除重复记录的方法,使用为例rowid DELETE FROM EMP E WHERE E.ROWID gt; (SELECT MIN(X.ROWID) FROM EMP X WHERE X.EMP

最高效删除重复记录的方法,使用为例rowid

DELETE FROM EMP E WHERE E.ROWID > (SELECT MIN(X.ROWID) FROM EMP X WHERE X.EMP_NO = E.EMP_NO);

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

Oracle查询删除表中重复记录