문제
Table: Users
+---------------+---------+
| Column Name | Type |
+---------------+---------+
| id | int |
| name | varchar |
+---------------+---------+
id is the column with unique values for this table.
name is the name of the user.
Table: Rides
+---------------+---------+
| Column Name | Type |
+---------------+---------+
| id | int |
| user_id | int |
| distance | int |
+---------------+---------+
id is the column with unique values for this table.
user_id is the id of the user who traveled the distance "distance".
Write a solution to report the distance traveled by each user.
Return the result table ordered by travelled_distance in descending order, if two or more users traveled the same distance, order them by their name in ascending order.
The result format is in the following example.
https://leetcode.com/problems/top-travellers/description/
예시
Input:
Users table:
+------+-----------+
| id | name |
+------+-----------+
| 1 | Alice |
| 2 | Bob |
| 3 | Alex |
| 4 | Donald |
| 7 | Lee |
| 13 | Jonathan |
| 19 | Elvis |
+------+-----------+
Rides table:
+------+----------+----------+
| id | user_id | distance |
+------+----------+----------+
| 1 | 1 | 120 |
| 2 | 2 | 317 |
| 3 | 3 | 222 |
| 4 | 7 | 100 |
| 5 | 13 | 312 |
| 6 | 19 | 50 |
| 7 | 7 | 120 |
| 8 | 19 | 400 |
| 9 | 7 | 230 |
+------+----------+----------+
Output:
+----------+--------------------+
| name | travelled_distance |
+----------+--------------------+
| Elvis | 450 |
| Lee | 450 |
| Bob | 317 |
| Jonathan | 312 |
| Alex | 222 |
| Alice | 120 |
| Donald | 0 |
+----------+--------------------+
Explanation:
Elvis and Lee traveled 450 miles, Elvis is the top traveler as his name is alphabetically smaller than Lee.
Bob, Jonathan, Alex, and Alice have only one ride and we just order them by the total distances of the ride.
Donald did not have any rides, the distance traveled by him is 0.
문제 풀이
SELECT u.name,
IFNULL(SUM(distance), 0) AS travelled_distance
FROM users AS u
LEFT JOIN rides AS r
ON u.id = r.user_id
GROUP BY u.id
ORDER BY travelled_distance DESC, name;SQL을 독학하시는 분들에게 도움이 되길 바라며,
혹 더 좋은 방법이 있거나 오류가 있다면 편하게 말씀 부탁드립니다.
