ORACLE 去除多餘的重複記錄語句

一，去除多餘的重複記錄，以下以判斷a字段，如果字段相同則記錄相同
1、使用 rowid的方式
①正常版

delete from stu
where
a in (select a from stu group by a having count(a)>1)
and
rowid not in (select min(rowid) from people group by a having count(a)>1);

② 簡便版

 delete from stu
 where rowid not in (select min(rowid) from stu group by a);

③ 使用表連接和 rowid 的方式

delete from stu t1 
where rowid not in (select min(rowid) from stu t2 where t1.a=t2.a);

二，以多個字段判定記錄相同，原理相同（如 a,b 字段）

delete from stu
where
stu.a,stu.b in (select a,b from stu group by a,b having count(*)>1)
and
rowid not in (select min(rowid) from people group by a,b having count(a)>1);

 delete from stu
 where rowid not in (select min(rowid) from stu group by a,b);