# $550. 游戏玩法分析 IV
# https://leetcode-cn.com/problems/game-play-analysis-iv/

# SQL架构
Create table If Not Exists Activity (player_id int, device_id int, event_date date, games_played int);
Truncate table Activity;
insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-03-01', '5');
insert into Activity (player_id, device_id, event_date, games_played) values ('1', '2', '2016-03-02', '6');
insert into Activity (player_id, device_id, event_date, games_played) values ('2', '3', '2017-06-25', '1');
insert into Activity (player_id, device_id, event_date, games_played) values ('3', '1', '2016-03-02', '0');
insert into Activity (player_id, device_id, event_date, games_played) values ('3', '4', '2018-07-03', '5');

# Write your MySQL query statement below
select
    round(avg(a.event_date is not null), 2) as fraction
from
    (
        select
            player_id,
            min(event_date) as login
        from
            Activity
        group by
            player_id
    ) tmp
    left join Activity a on tmp.player_id = a.player_id
    and datediff(a.event_date, tmp.login) = 1;

# clean-up
drop table Activity;