Question

这不是我的原始查询，这是一位绅士在http://elliot.land/发表的查询。这是ELO评分系统的脚本。我的问题是，我已经尝试了很多次，但是我不知道如何将POSTGRESQL（RECURSIVE）转换为TSQL（CTE）。有人可以帮助我进行转换吗？这是数据：

CREATE TABLE plays (
game_number INT          NOT NULL, -- must be consecutive and start at 1!
p1name      VARCHAR(255) NOT NULL, -- first player
p1score     FLOAT        NOT NULL, -- 0 or 1
p2name      VARCHAR(255) NOT NULL, -- second player
p2score     FLOAT        NOT NULL  -- 0 or 1
);

INSERT INTO plays VALUES
(1, 'Elliot', 0, 'Brendan', 1),
(2, 'Bob', 1, 'Brendan', 0),
(3, 'Bob', 1, 'Elliot', 0),
(4, 'Jane', 1, 'Bob', 0),
(5, 'Bob', 0, 'Brendan', 1),
(6, 'Jane', 1, 'Elliot', 0);

以下是我需要帮助进行转换的公式：

WITH RECURSIVE p(current_game_number) AS (
WITH players AS (
SELECT DISTINCT p1name AS player_name
FROM plays
UNION
SELECT DISTINCT p2name
FROM plays
)
SELECT
0               AS game_number,
player_name,
1000.0 :: FLOAT AS previous_elo,
1000.0 :: FLOAT AS new_elo
FROM players
UNION ALL
(
WITH previous_elos AS (
    SELECT *
    FROM p
)
SELECT
  plays.game_number,
  player_name,
  previous_elos.new_elo AS previous_elo,
  round(CASE WHEN player_name NOT IN (p1name, p2name)
    THEN previous_elos.new_elo
        WHEN player_name = p1name
          THEN previous_elos.new_elo + 32.0 * (p1score - (r1 / (r1 + r2)))
        ELSE previous_elos.new_elo + 32.0 * (p2score - (r2 / (r1 + r2)))          END)
FROM plays
  JOIN previous_elos
    ON current_game_number = plays.game_number - 1
  JOIN LATERAL (
       SELECT
         pow(10.0, (SELECT new_elo
                    FROM previous_elos
                    WHERE current_game_number = plays.game_number - 1 AND player_name = p1name) / 400.0) AS r1,
         pow(10.0, (SELECT new_elo
                    FROM previous_elos
                    WHERE current_game_number = plays.game_number - 1 AND player_name = p2name) / 400.0) AS r2
       ) r
    ON TRUE
 )
 )
 SELECT
 player_name,
 (
 SELECT new_elo
 FROM p
 WHERE t.player_name = p.player_name
 ORDER BY current_game_number DESC
 LIMIT 1
 )                    AS elo,
count(CASE WHEN previous_elo < new_elo
THEN 1
    ELSE NULL END) AS wins,
count(CASE WHEN previous_elo > new_elo
THEN 1
    ELSE NULL END) AS losses
FROM
(
SELECT *
FROM p
WHERE previous_elo <> new_elo
ORDER BY current_game_number, player_name
) t
GROUP BY player_name
ORDER BY elo DESC;

SQL查询中的ELO公式

0 个答案: