plsql 异常

http://chenhua-1984.iteye.com/blog/990970

http://chenhua-1984.iteye.com/blog/996018

?

begin

  begin  while(true)  loop    select seq_user_number.nextval into result from dual;    select user_number into user_number from  user_number where user_number=result;    end loop; exception     when no_data_found then         dbms_output.put_line(result);   end;    return result;end;