SQL面试50题-15

查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩（重点）
知识点：平均成绩--统计 GROUP BY 语句

1.查询两门以上不及格课程的同学学号
SELECT s_id FROM Score WHERE s_score <60 GROUP BY s_id HAVING COUNT(s_score) >= 2
2.要同时选取学号和成绩就要联结Student和Score表
完整代码：

SELECT stu.s_id,stu.s_name,AVG(sco.s_score) FROM Student stu
INNER JOIN Score sco ON sco.s_id = stu.s_id
GROUP BY stu.s_id
HAVING stu.s_id IN 
(SELECT s_id FROM Score WHERE s_score <60 GROUP BY s_id HAVING COUNT(s_score) >= 2);