MySQL中的if和case语句使用总结

Posted 2021-01-07 weibanggang

create table test(
id int primary key auto_increment,
name varchar(20),
sex int 
)
insert into test(name,sex) values(‘小明‘,1),(‘小兰‘,0),(‘小邹‘,1),(‘小孟‘,0)

select id ,name ,if(sex=1,‘男‘,‘女‘) from test

select id ,name ,case sex when 1 then ‘男‘ else ‘女‘ end as sex from test

　　if([字段名]=[条件],[为真时返回],[为假时返回])

　　case [字段名] when [条件] then [为真时返回] else [为假时返回] end as sex from test

 　　case [字段名] when [条件] then [为真时返回]  end as sex from test  (该语句为假时候返回null)