相关表数据:
- Score_info表
2、Student_info表
3、Course_info表
4、Teacher_info 表
题目及思路解析:
多表连接
题目:查询所有课程成绩在70分以上的学生的姓名、课程名称和分数,按分数升序排列
第一种:
select
sc.stu_id,
stu_name,
course_name,
score
from score_info sc
left join student_info st on st.stu_id = sc.stu_id
left join course_info ci on sc.course_id = ci.course_id
where score>70;
第二种:
代码:
select
s.stu_id,
s.stu_name,
c.course_name,
s2.score
from student_info s
join (
select
stu_id,
sum(if(score >= 70,0,1)) flage
from score_info
group by stu_id
having flage =0
) t1
on s.stu_id = t1.stu_id
left join score_info s2 on s.stu_id = s2.stu_id
left join course_info c on s2.course_id = c.course_id;
思路解析:
说明补充: