mysql程序成功删除一些日期但返回null为row_count（）

Question

当我执行{select @ leftnum，@ deletenum;}时，它总是返回null，但它删除了日期，因为我对于池英语的例外情况。

    delimiter //
    CREATE PROCEDURE  REMOVEandreturn3( IN NUM INT ,
                                         out leftnum int  ,
                                         out deletenum int)
    BEGIN
    DELETE FROM ORDERS2
    WHERE  ORDER_NUM = NUM ;
    select  count(order_num) 
    from orders2  into leftnum;
    select  row_count()  
    from orders2 into deletenum;
    END//
    delimiter ;
    call removeandreturn2  (20007,@leftnum,@deletenum);
    select *from orders2;
    select @leftnum,@deletenum ;