CASE WHEN

create table Studento
(

id int,
name varchar(20),
score int

);

insert into studento
values

(1,'张三',92),

(2,'李四',76),
(3,'王五',55),
(4,'赵六',85);

select
id,
name,
score,
case
when score >= 90 then '优秀'
when score >= 70 then '良好'
when score >= 60 then '及格'
else '不及格'
end as 等级
from studento;

create table UserInfo
(

name varchar(20),
sex int

);

insert into UserInfo values
('张三',1),('李四',2);

SELECT
name,
CASE sex
WHEN 1 THEN '男'
WHEN 2 THEN '女'
ELSE '未知'
END AS 性别
FROM UserInfo;