列标签
select id,name from student;
select id as '学号'，name as '姓名' from student;(只是修改结果)
排序
select * from student where sex='1'
order by sno asc,sname desc
ps:ASC正序排序；DESC逆序排序
IN、LIKE、IS NULL
select * from student
where id IN('2020001','2020002','2020003')
where id NOT IN('2020001','2020002','2020003')
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select * from student
where phone IS NULL
select * from student
where phone IS NOT NULL
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select * from student where sname LIKE '张%'
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ps:‘%’是通配符
常用函数
selece * from student where year(birthday)>=1980
and year(birthday)<1990
注：查询90后的信息
select max(id) from student
表的关联
SELECT stu.sname,stu.sage,stu.sno,sc.sno,sc.score
FROM student stu,score sc //起别名
WHERE stu.sno=sc.sno