博主最近在學習數據庫，今天給大家分享下數據庫的一些基本查詢語法，就拿班級學生人數成績來舉例子吧
1 根據Class_id對班級女生進行降序排序
//*代表所有列
select * from student where gender = ‘女’
order by class_id desc;
insert into score values(6,3,1,50);
select * from score;
//根據course_id升序，,number desc降序查詢score表的所有信息
select * from score order by course_id ,number desc;
//查詢student中女生的數量
select count(*) from student where gender = ‘女’;
//查詢最高法
select max(number) from score;
//查詢最高分的人的 student_id,course_id ；
select student_id,course_id from score where number = (select max(number) from score);
//查詢一行一列
select * from score order by number desc limit 0,1;
查詢某一列的平均數據
select course_id ‘學科號’, avg(number) as ‘平均成績’ from score group by course_id;
select avg(number) as ‘平均成績’ from score;
//查詢某一列中大於70小於90的數據
select student_id from score where number >70 and number<90;
查詢所有學生的Sname,Cno,Degree列
select Sname,Cno,Degree from Score,student where Score.Sno=student.sno;
查詢以某個數或者其他開頭的
select*from score where Cno like ‘3%’;