oracle partition by 去除重复记录（多个字段）

delete 表名 a where not exists(
       select b.rd from (select rowid rd,row_number()over(
       partition by 替重字段一，替重字段二，替重字段三 order by 替重字段一/二/三) rn
       from 表名) b where b.rn=1 and a.rowid = b.rd
);