TopTravellers.md

Top Travellers

• SQL Schema

Create Table If Not Exists Users (id int, name varchar(30))
Create Table If Not Exists Rides (id int, user_id int, distance int)
Truncate table Users
insert into Users (id, name) values ('1', 'Alice')
insert into Users (id, name) values ('2', 'Bob')
insert into Users (id, name) values ('3', 'Alex')
insert into Users (id, name) values ('4', 'Donald')
insert into Users (id, name) values ('7', 'Lee')
insert into Users (id, name) values ('13', 'Jonathan')
insert into Users (id, name) values ('19', 'Elvis')
Truncate table Rides
insert into Rides (id, user_id, distance) values ('1', '1', '120')
insert into Rides (id, user_id, distance) values ('2', '2', '317')
insert into Rides (id, user_id, distance) values ('3', '3', '222')
insert into Rides (id, user_id, distance) values ('4', '7', '100')
insert into Rides (id, user_id, distance) values ('5', '13', '312')
insert into Rides (id, user_id, distance) values ('6', '19', '50')
insert into Rides (id, user_id, distance) values ('7', '7', '120')
insert into Rides (id, user_id, distance) values ('8', '19', '400')
insert into Rides (id, user_id, distance) values ('9', '7', '230')

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.

Example 1:

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.

Solution:

select name, sum(ifnull(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