要求；
存储过程要有输入和输出
create procedure chengji( in n int , out result varchar )
begin
declare result varchar(20);
set n=truncate(rand()*100,0);
case
when n>90 then
set result='A';
when n>80 then
set result='B';
when n>70 then
set result='C';
when n>60 then
set result='D';
else
set result='E';
end case;
select n,result ;
end;
call chengji;create procedure RiQi( in n int , out result varchar (20) )
begin
case n
when 0 then
set result='星期日';
when 1 then
set result='星期一';
when 2 then
set result='星期二';
when 3 then
set result='星期三';
when 4 then
set result='星期四';
when 5 then
set result='星期五';
else
set result='星期六';
end case;
end;
call RiQi(0,@result);
select @result;
