_511.sql

--511. Game Play Analysis I
--
--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 game.
--Each row is a record of a player who logged in and played a number of games (possibly 0) before logging out on some day using some device.
--
--
--Write an SQL query that reports the first login date for each player.
--
--The query result format is in the following example:
--
--Activity table:
--+-----------+-----------+------------+--------------+
--| player_id | device_id | event_date | games_played |
--+-----------+-----------+------------+--------------+
--| 1         | 2         | 2016-03-01 | 5            |
--| 1         | 2         | 2016-05-02 | 6            |
--| 2         | 3         | 2017-06-25 | 1            |
--| 3         | 1         | 2016-03-02 | 0            |
--| 3         | 4         | 2018-07-03 | 5            |
--+-----------+-----------+------------+--------------+
--
--Result table:
--+-----------+-------------+
--| player_id | first_login |
--+-----------+-------------+
--| 1         | 2016-03-01  |
--| 2         | 2017-06-25  |
--| 3         | 2016-03-02  |
--+-----------+-------------+

--# Write your MySQL query statement below

select player_id, min(event_date) as first_login
from Activity
group by player_id