练习3--查询全部同窗的学生编号、学生姓名、选课总数、全部课程的总成绩

查询全部同窗的学生编号、学生姓名、选课总数、全部课程的总成绩

--解法一：

select t2.s_id, t2.s_name, count(t1.c_id) as sun_course, sum(t1.s_score) as sum_score from student t2 left join score t1 on t1.s_id = t2.s_id group by t1.s_id

 

--参考解法：

select a.s_id, a.s_name, count(b.c_id) as sum_course, sum(b.s_score) as sum_score from student a left join score b on a.s_id = b.s_id group by a.s_id, a.s_name;

 

--2019/04/17