MySQL 8.0

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select version();


version()


8.0.23


CREATE TABLE score
(
  id INTEGER             NOT NULL AUTO_INCREMENT PRIMARY KEY,
  result CHAR(1)         NOT NULL,
  die_1 TINYINT UNSIGNED NOT NULL,
  die_2 TINYINT UNSIGNED NOT NULL,
  player_id INTEGER      NOT NULL,
  
  CONSTRAINT result_w_l_ck  CHECK (result IN ('W', 'L')),
  CONSTRAINT die_1_throw_ck CHECK (die_1 BETWEEN 1 AND 6),
  CONSTRAINT die_2_throw_ck CHECK (die_2 BETWEEN 1 AND 6)
  
);
INSERT INTO score VALUES
(1,	'L',	4,	4,	9),
(2,	'L',	4,	5,	7),
(3,	'W',	4,	3,	9),
(4,	'L',	2,	3,	9),
(5,	'W',	6,	1,	7),
(6,	'W',	1,	6,	7),
(7,	'L',	1,	3,	7);
SELECT 
  player_id,
  SUM(CASE 
    WHEN result = 'W' THEN 1
    ELSE 0
  END) AS wins,
  SUM(CASE 
    WHEN result = 'L' THEN 1
    ELSE 0
  END) AS losses,
  COUNT(player_id) AS cnt,
  (SUM(CASE 
    WHEN result = 'W' THEN 1
    ELSE 0
  END))/(COUNT(player_id)) AS w_proportion,
  
  ROUND((SUM(CASE 
    WHEN result = 'W' THEN 1
    ELSE 0
  END))/(COUNT(player_id)) * 100, 2) AS w_percent  
  
FROM score
GROUP BY player_id
ORDER BY player_id;


player_id
wins
losses
cnt
w_proportion
w_percent


7
2
2
4
0.5000
50.00

9
1
2
3
0.3333
33.33