Game Play Analysis II

Problem

Table: Activity

+--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| player_id    | int     |
| device_id    | int     |
| event_date   | date    |
| games_played | int     |
+--------------+---------+
(player_id, event_date) is the primary key of this table.
This table shows the activity of players of some games.
Each row is a record of a player who logged in and played a number of games (possibly 0) before logging out on someday using some device.

Write an SQL query to report the device that is first logged in for each player.

Return the result table in any order.

Solution

The problem Game Play Analysis II can be solved using the keyword IN with the query from Game Play Analysis I as a subquery.

Implementation

# Write your MySQL query statement below

SELECT player_id, device_id
FROM activity
WHERE
  (player_id, event_date) IN (
    SELECT player_id, MIN(event_date)
    FROM activity
    GROUP BY player_id
  );