oracle通过游标方式删除所有以NO开头的session

declare
             cursor   cur_sess   is
                   select   sid,   serial#
                      from   v$session
                     where   
                          username like 'NO%';
           w_sid   number;
             w_serial   number;
         begin
           open   cur_sess;
           loop
               fetch   cur_sess   into   w_sid,w_serial;
               if   cur_sess%notfound   then
                   exit;
              end   if;
               execute   immediate   'alter   system   kill   session   '''||w_sid|| ', '||w_serial|| '''';
           end   loop;
     end;