oracle数据库删除重复数据

使用伪列，rowid，保留rowid最小的那个记录

          create table a (id  varchar2(10),name varchar2(20));

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