How can Update table column with the virtual column? I want to update repetitive columns, And I build virtual column for did this. I can "select" but can't "update"

Here is SQL Fiddle :

http://sqlfiddle.com/#!9/d09189/3

Also Code review :

I have this table :

CREATE TABLE game_log (
    user_id int,
    game_id int,
    day_number int,
    game_detail int,
    wallp_det int );

INSERT INTO game_log (user_id, game_id, day_number, game_detail, wallp_det)
VALUES (11,21, 1,12,14),           
       (11,21, 2,18,24),
       (11,22, 3,20, 1),
       (11,22, 4,25,30),
       (11,23, 5, 5, 2),
       (12,21, 6,25,10),
       (12,22, 7,12,22),
       (12,22, 8,23, 2),
       (12,23, 9, 4,12),
       (13,21,10, 9, 8),
       (13,21,11,28,38);




I can "select" but can't "update" :

SET @s := 0;
select  sum(game_detail)  As ga_datail, user_id,game_id, @s := @s + 1 As day_num
from game_log 
group by user_id,game_id;


After this, I will delete repetitive rows

what I have :

   user_id  | game_id |  day_number | game_detail |   wallp_det
    ------  |---------|-------------|-------------|--------
    11      | 21      |  1          | 12          |  14
    11      | 23      |  2          | 18          |  24
    11      | 22      |  3          | 20          |  1
    11      | 23      |  4          | 25          |  30
    11      | 23      |  5          | 5           |  2
    12      | 21      |  6          | 25          |  10
    12      | 22      |  7          | 12          |  22
    12      | 23      |  8          | 23          |  2
    12      | 23      |  9          | 4           |  12
    13      | 21      |  10         | 9           |  8
    13      | 21      |  11         | 28          |  38


-
what i want :

   user_id  | game_id |  day_number | game_detail |   wallp_det
    ------  |---------|-------------|-------------|--------
    11      | 21      |  1          | 12          |  14
    11      | 23      |  0          | 48          |  56
    11      | 22      |  3          | 20          |  1
    12      | 21      |  6          | 25          |  10
    12      | 22      |  7          | 12          |  22
    12      | 23      |  0          | 27          |  14
    13      | 21      |  0          | 37          |  46


Thanks in advance.
I solved it this way :

INSERT INTO game_log (game_detail,user_id,game_id,day_number)
select  sum(game_detail) As game_datail,user_id,game_id,0   from game_log group by user_id,game_id


--

DELETE FROM game_log where day_number != 0