Oracle 刪除重複資料只留一條

查詢及刪除重複記錄的SQL語句

 

1、查詢表中多餘的重複記錄，重複記錄是根據單個欄位（Id）來判斷

 

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

 

2、刪除表中多餘的重複記錄，重複記錄是根據單個欄位（Id）來判斷，只留有rowid最小的記錄

 

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

 

3、查詢表中多餘的重複記錄（多個欄位）

 

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

 

4、刪除表中多餘的重複記錄（多個欄位），只留有rowid最小的記錄

 

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)

 

5、查詢表中多餘的重複記錄（多個欄位），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)

出處:http://www.cnblogs.com/252e/archive/2012/09/13/2682817.html