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 | +---------+
# Write your MySQL query statement below select courses_cnt.class from (select count(DISTINCT student)as cnt,class from courses where 1=1 group by class) as courses_cnt where courses_cnt.cnt >= 5
LeetCode - 596. Classes More Than 5 Students
原文：http://www.cnblogs.com/wxisme/p/7517368.html