[LeetCode] 596. Classes More Than 5 Students_Easy tag:SQL
2018-08-20 03:03 Johnson_强生仔仔 阅读(180) 评论(0) 编辑 收藏 举报There is a table courses
with columns: student and class
Please list out all classes which have more than or equal to 5 students.
For example, the table:
+---------+------------+ | student | class | +---------+------------+ | A | Math | | B | English | | C | Math | | D | Biology | | E | Math | | F | Computer | | G | Math | | H | Math | | I | Math | +---------+------------+
Should output:
+---------+ | class | +---------+ | Math | +---------+
Note:
The students should not be counted duplicate in each course.
Code #用distinct是因为有可能有学生多次选了该门课
SELECT class FROM courses GROUP BY class HAVING COUNT(DISTINCT student) >= 5