编写带参数的存储过程，将百分制成绩，转换成绩等级’A’,’B’,’C’,’D’,’E’

要求；

1. 存储过程要有输入和输出

create procedure chengji(inout i int)

begin

declare n int;

declare result varchar(20);

set n=i;

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;

set @x=40;

call chengji(@x);

select @x;