流程控制语句Mysql的代码实例讲解

流程控制语句mysql的代码实例讲解

####################流程控制语句 
-- 1.顺序控制语句 begin..end...
delimiter //
create function max1(i int,j int)
returns int
begin
    return (select * from student where 学号=xh);
end //
delimiter ;

-- 2.分支控制语句 
/* if ...then...;
   else....;
   end if;
*/
delimiter //
create function f1(j int)
returns int
begin 
    declare i int;
    if i%2 =0 then
        return 0;
	else 
        return 1;
	end if;
end //
delimiter ;

select f1(23);

/*case语句
case....when...then...;
		when...then...;
        else...;
end case;
        */
delimiter //
create function scorel(i int)
returns char(6)
begin 
    declare j int;
    declare cj char(6);
	case 
		when j>=90 then set cj= '优秀';
		when j>=80 and j<90 then set cj='良好';
		when j>=70 and j<80 then set cj='中等';
		when j>=60 and j<70 then set cj='及格';
		else set cj='不及格';
	 end case;
     return cj;
end //
delimiter ;
     
-- 3.循环控制语句 
/*while...do
...;
end while;
*/

delimiter ##
create function sum1()
returns int
begin
declare s int default 0;
declare i int default 1;
while i<=100 do
set s=s+i;
set i=i+1;
end while;
return s;
end##
delimiter ;