add 1407

Author: fishercoder1534

README.md

@@ -940,6 +940,7 @@ _If you like this project, please leave me a star._ ★
 
 |  #  |      Title     |   Solutions   | Video         | Difficulty    | Tag          
 |-----|----------------|---------------|---------------|---------------|-------------
+|1407|[Top Travellers](https://leetcode.com/problems/top-travellers/)|[Solution](../master/database/_1407.sql) || Easy |
 |1384|[Total Sales Amount by Year](https://leetcode.com/problems/total-sales-amount-by-year/)|[Solution](../master/database/_1384.sql) || Hard |
 |1378|[Replace Employee ID With The Unique Identifier](https://leetcode.com/problems/replace-employee-id-with-the-unique-identifier/)|[Solution](../master/database/_1378.sql) || Easy |
 |1369|[Get the Second Most Recent Activity](https://leetcode.com/problems/get-the-second-most-recent-activity/)|[Solution](../master/database/_1369.sql) || Hard |

database/_1407.sql

@@ -0,0 +1,86 @@
+--1407. Top Travellers
+--
+--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.
+--city_id is the id of the city who bought the product "product_name".
+--
+--
+--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.
+--
+--# Write your MySQL query statement below
+
+--credit: https://leetcode.com/problems/top-travellers/discuss/572803/MySQL-Simple-Solution
+select name, sum(ifnull(distance, 0)) as travelled_distance
+from rides r
+right join users u
+on r.user_id = u.id
+group by name
+order by 2 desc,1 asc;