MySQL分支和循环结构方式

select *,
	case role_id 
		when 1 then "管理员" 
		when 2 then "普通用户" 
		else "游客" end
	as role
from user_p;

select *,case
	when age <19 then "少年"
	when age <30 then "青年"
	when age >30 and age <50 then "中年"
	else "老年"
	end "状态"
from info;

#定义分号
DELIMITER $$
# # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
CREATE FUNCTION age_status(age int) RETURNS varchar(20)
BEGIN
  
    DECLARE status varchar(20)  DEFAULT "老年";
 
    IF age < 19  THEN SET status ="少年";
    ELSEIF age <30 THEN SET status ="青年";
    ELSEIF 30<age<50 THEN SET status ="中年";
    ELSE SET status ="老年";
    END IF;
    RETURN status;
END $$
# # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
#重新定义分号
DELIMITER ;
# # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
 select age_status(45);

DELIMITER $$
# # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
CREATE FUNCTION insertUser(num INT) RETURNS varchar(15)
BEGIN 

    DECLARE i INT DEFAULT(1);
   
    while i<= num DO
        INSERT INTO info(name,sex,classname,age) 
		VALUES (CONCAT("name",i),CONCAT("sex",i),CONCAT("classname",i),i);
        SET i=i+1;
        END WHILE;
	RETURN "success";
END $$
# # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
DELIMITER ;
# # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
select insertUser(5);