oracle 刪除資料表中的重複

/* 重複資料刪除的反饋表的資料*/  procedure PRO_CZW_DEL_DOU_FEEBACK as  begin    begin      for rec in (select row_number() over(           partition by t.ywlsh  /*指定的重複列*/           order by t.id desc) as lev, /*指定的重複列的排序*/                         t.*                    from T_CZW_YW_FEEDBACK t                   where exists (select 1                            from T_CZW_YW_FEEDBACK k                           where k.ywlsh = t.ywlsh                           group by k.ywlsh                          having count(*) > 1)) loop        if rec.lev = 1 then          null;        else          delete T_CZW_YW_FEEDBACK t where t.id = rec.id;        end if;      end loop;    end;    commit;  end PRO_CZW_DEL_DOU_FEEBACK;