[SQL30] Use sum() over() to find the cumulative amount of play for each player

There is an activity table as follows

player_id   device_id   event_date      games_played
1           2           '2016-01-01'    5
1           2           '2016-05-02'    6
1           3           '2017-07-25'    1
3           1           '2016-03-02'    0
3           4           '2018-07-03'    5

Where games_played is the number of games that players log in to play,

Query how many games each player has played every day? The results are as follows:

player_id   event_date      games_played_so_far
1           '2016-01-01'    5
1           '2016-05-02'    11
1           '2017-07-25'    12
3           '2016-03-02'    0
3           '2018-07-03'    5

Explanation: Player 1 played 5 for the first time, so it is 5, and the second time is 6, so the total is 5+6=11, and the
third time is 1, the total is 5+6+1=12
Player 2 similar

solve:

select player_id
      ,event_date
      ,sum(games_played) over(partition by player_id order by event_date) as games_played_so_far
  from activity
;
player_id   event_date      games_played_so_far
1           2016-01-01      5
1           2016-05-02      11
1           2017-07-25      12
3           2016-03-02      0
3           2018-07-03      5

备注：建表和数据
create table activity(player_id int,device_id int,event_date date,games_played int);
insert into activity values(1,2,'2016-01-01',5);
insert into activity values(1,2,'2016-05-02',6);
insert into activity values(1,3,'2017-07-25',1);
insert into activity values(3,1,'2016-03-02',0);
insert into activity values(3,4,'2018-07-03',5);