Mysql查询进阶

#查询“生物”课程比“物理”课程成绩高的所有学生的学号；

 #需要用到临时表、连表、条件删选等知识点

SELECT A.student_id FROM
(SELECT sid,student_id,cname,num FROM score LEFT JOIN course on score.course_id=course.cid WHERE cid=1) AS A
INNER JOIN
(SELECT sid,student_id,cname,num FROM score LEFT JOIN course on score.course_id=course.cid WHERE cid=2) AS B
on A.student_id=B.student_id WHERE A.num > B.num

#查询没学过“叶平”老师课的同学的学号、姓名；

#用到连表查询、多层查询、条件判断等知识点

SELECT sid,sname FROM student WHERE sid NOT IN (SELECT student_id FROM score WHERE course_id IN (SELECT course.cid FROM teacher LEFT JOIN course on teacher.tid=course.teacher_id where teacher_id = 2) GROUP BY student_id);

* 参考oldboy视频整理