有一个courses 表 ,有: student (学生) 和 class (课程)。
请列出所有超过或等于5名学生的课。
例如,表:
student | class |
---|---|
A | Math |
B | English |
C | Math |
D | Biology |
E | Math |
F | Computer |
G | Math |
H | Math |
I | Math |
应该输出:
class |
---|
Math |
Note:
学生在每个课中不应被重复计算。
解答
SELECT
class
FROM (
SELECT
class,
count(DISTINCT student) as amount
FROM courses
GROUP BY class
) t
WHERE amount >= 5
原题
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/classes-more-than-5-students