Question

查询所有至少选修２门课程的学生的学号的语句怎么写？

在数据库里面！

Answer 1

⑥
SELECT DISTINCT X.S#
FROM SC AS X, SC AS Y
WHERE X.S#=Y.S# AND X.C#!=Y.C#;

Answer 2

SELECT DISTINCT X.S#
FROM SC AS X,SC AS Y
WHERE X.S#=Y.S# AND X.C# != Y.C#;

Answer 3

Selece 学号 from 表 条件(选修课程大于或等于2的不就行了么)

Answer 4

select 学号
from 选课表
group by 学号
having count(学号)>=2