SQL有关group by的疑惑

Question

如果想依据SNo(学号)分组并输出每一小组对应的CNo（课程号）和Score（成绩），要怎么办？

Answer 1

select SNo,CNo,sum(Score) Score from test.SC group by SNo,CNo;
或者
select * from test.SC order by SNo,CNo;