1、查找表中多余的重復記錄，重復記錄是根據單個字段(Id)來判斷

select * from 表 where Id in (select Id from 表 group byId having count(Id) > 1)

2、刪除表中多余的重復記錄，重復記錄是根據單個字段(Id)來判斷，只留有rowid最小的記錄

DELETE from 表 WHERE (判斷字段) IN ( SELECT 判斷字段 FROM 表 GROUP BY 判斷字段 HAVING COUNT(判斷字段) > 1) AND ROWID NOT IN (SELECT MIN(ROWID) FROM 表 GROUP BY id HAVING COUNT(*) > 1);

注意：AND后面的句子獲取到的是除去擁有rowid最小的所有的記錄(單個不重復記錄也包含)，Where 與 AND之間是獲取所有含有重復記錄的字段。

3、查找表中多余的重復記錄(多個字段)

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

4、刪除表中多余的重復記錄(多個字段)，只留有rowid最小的記錄(原理同2)

delete from 表 a where (a.Id,a.seq) in (select Id,seq from 表 group by Id,seq having count(*) > 1) and rowid not in (select min(rowid) from 表 group by Id,seq having count(*)>1)

示例二：delete from student where s_id not in(select min(s_id) from student group by s_name,c_id);

5、查找表中多余的重復記錄(多個字段)，不包含rowid最小的記錄

select * from 表 a where (a.Id,a.seq) in (select Id,seq from 表 group by Id,seq having count(*) > 1) and rowid not in (select min(rowid) from 表 group by Id,seq having count(*)>1)

原文：http://www.cnblogs.com/cnblog-long/p/7095923.html

總結

以上是生活随笔為你收集整理的oracle 保留一个记录吗,笔记：Oracle查询重复数据并删除，只保留一条记录的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。