문제
Table: Courses
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| student | varchar |
| class | varchar |
+-------------+---------+
(student, class) is the primary key (combination of columns with unique values) for this table.
Each row of this table indicates the name of a student and the class in which they are enrolled.
Write a solution to find all the classes that have at least five students.
Return the result table in any order.
The result format is in the following example.
https://leetcode.com/problems/classes-more-than-5-students/description/
Classes More Than 5 Students - LeetCode
Can you solve this real interview question? Classes More Than 5 Students - Table: Courses +-------------+---------+ | Column Name | Type | +-------------+---------+ | student | varchar | | class | varchar | +-------------+---------+ (student, class) is the
leetcode.com
예시
Input:
Courses table:
+---------+----------+
| student | class |
+---------+----------+
| A | Math |
| B | English |
| C | Math |
| D | Biology |
| E | Math |
| F | Computer |
| G | Math |
| H | Math |
| I | Math |
+---------+----------+
Output:
+---------+
| class |
+---------+
| Math |
+---------+
Explanation:
- Math has 6 students, so we include it.
- English has 1 student, so we do not include it.
- Biology has 1 student, so we do not include it.
- Computer has 1 student, so we do not include it.
문제 풀이
SELECT class
FROM courses
GROUP BY class
HAVING COUNT(*) >= 5;SQL을 독학하시는 분들에게 도움이 되길 바라며,
혹 더 좋은 방법이 있거나 오류가 있다면 편하게 말씀 부탁드립니다.
