Problem
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.
Solution
SQL
1 2 3 |
# Author: Huahua # Running time: 1756 ms select class from courses group by class having count(distinct student) >= 5 |
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