LeetCode 1407. Top Travellers

Description

https://leetcode.com/problems/top-travellers/

SQL Schema

Table: Users

+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| id            | int     |
| name          | varchar |
+---------------+---------+
id is the primary key 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 primary key for this table.
user_id is the id of the user who travelled the distance "distance".

Write an SQL query to report the distance travelled by each user.

Return the result table ordered by travelled_distance in descending order, if two or more users travelled the same distance, order them by their name in ascending order.

The query result format is in the following example.

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      |
+------+----------+----------+

Result table:
+----------+--------------------+
| name     | travelled_distance |
+----------+--------------------+
| Elvis    | 450                |
| Lee      | 450                |
| Bob      | 317                |
| Jonathan | 312                |
| Alex     | 222                |
| Alice    | 120                |
| Donald   | 0                  |
+----------+--------------------+
Elvis and Lee travelled 450 miles, Elvis is the top traveller 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 didn't have any rides, the distance travelled by him is 0.

Explanation

COALESCE null as 0 and ORDER BY multiple columns.

SQL Solution

# Write your MySQL query statement below
select name, COALESCE(sum(distance), 0) as travelled_distance from Users left join Rides on Users.id = Rides.user_id group by user_id order by travelled_distance desc, name asc

Leave a Reply

Your email address will not be published.