LeetCode / 602. Friend Requests II: Who Has the Most Friends / MySQL(Medium) / Subquery

📚문제

출처 : LeetCode(https://leetcode.com/problems/friend-requests-ii-who-has-the-most-friends/)

📝풀이

# Write your MySQL query statement below
WITH cte_re AS(
SELECT requester_id AS id
     , COUNT(accepter_id) AS cnt
FROM RequestAccepted
GROUP BY requester_id)
,
cte_ac AS(
SELECT accepter_id AS id
     , COUNT(accepter_id) AS cnt
FROM RequestAccepted
GROUP BY accepter_id)
,
cte_union AS (
SELECT * FROM cte_re
UNION ALL
SELECT * FROM cte_ac)

SELECT id
     , SUM(cnt) AS num
FROM cte_union
GROUP BY id
ORDER BY num DESC
LIMIT 1

많이 어려운 문제는 아니었지만

개념과 풀이 방향을 구글링하여 찾았으므로

다음에 꼭 다시 풀어보자🧐