Question

对于体育锦标赛，人们在另外一组2名球员中成对比赛时，我想输出一个特定球员面对的每个对手的名单，以及比赛中的胜负，抽奖和失利数量特定玩家和对手之间。

例如，如果结果是：

播放器1＆amp;播放器2 2-1播放器3＆amp;玩家4
玩家3＆amp;球员1 1-0球员2＆amp;玩家4
播放器2＆amp;玩家4 4-2玩家1＆amp;球员3
播放器1＆amp;球员4 0-0球员3＆amp;玩家2

我希望播放器1的输出为：

玩家2，W1 D1 L1
玩家3，W1 D1 L0
玩家4，W2 D0 L1

这已经证明难以实现。我的数据分为两个表格，一个包含所有玩家（玩家）和一个得分表（分数）的表格。

玩家拥有PlayerID和PlayerName字段。

分数有字段Player1，Player2，Player3，Player4和Score，其中每个Player字段可以包含任何PlayerID（因此任何给定的ID可以根据行显示在不同的列中），并且存储分数，如果它少于21，播放器1＆amp; 2输了，如果大于21，他们就赢了。

此查询有什么问题？显然它正在返回0。

SELECT opponent as opp, COUNT(result='win') as c1, COUNT(result='draw') as c2, COUNT(result='loss') as c3
      FROM (SELECT
            CASE
                WHEN '$player' IN(Players1.PlayerName, Players2.PlayerName) THEN Players3.PlayerName
                WHEN '$player' IN(Players3.PlayerName, Players4.PlayerName) THEN Players1.PlayerName
                ELSE 'NA' 
                END as opponent,
            CASE
                WHEN '$player' IN(Players1.PlayerName, Players2.PlayerName) 
                THEN
                    CASE
                        WHEN Scores.Score > 21 THEN 'win'
                        ELSE 'NA'
                        END as result,
                    CASE
                        WHEN Scores.Score < 21 THEN 'loss'
                        ELSE 'NA'
                        END as result,
                WHEN '$player' IN(Players3.PlayerName, Players4.PlayerName) 
                THEN
                    CASE
                        WHEN Scores.Score < 21 THEN 'win'
                        ELSE 'NA'
                        END as result,
                    CASE
                        WHEN Scores.Score > 21 THEN 'loss'
                        ELSE 'NA'
                        END as result,
                WHEN Scores.Score = 21 THEN 'draw'
                ELSE 'NA' 
                END as result,
        FROM Scores
        INNER JOIN Players Players1 ON Scores.Player1=Players1.PlayerID
        INNER JOIN Players Players2 ON Scores.Player2=Players2.PlayerID
        INNER JOIN Players Players3 ON Scores.Player3=Players3.PlayerID
        INNER JOIN Players Players4 ON Scores.Player4=Players4.PlayerID
        WHERE Players1.PlayerName = '$player' OR Players2.PlayerName = '$player' OR Players3.PlayerName = '$player' OR Players4.PlayerName = '$player'
        UNION ALL
        SELECT
            CASE
                WHEN '$player' IN(Players1.PlayerName, Players2.PlayerName) THEN Players4.PlayerName
                WHEN '$player' IN(Players3.PlayerName, Players4.PlayerName) THEN Players2.PlayerName
                ELSE 'NA' 
                END as opponent,
            CASE
                WHEN '$player' IN(Players1.PlayerName, Players2.PlayerName) AND Scores.Score > 21 THEN 'win'
                WHEN '$player' IN(Players1.PlayerName, Players2.PlayerName) AND Scores.Score < 21 THEN 'loss'
                WHEN '$player' IN(Players3.PlayerName, Players4.PlayerName) AND Scores.Score < 21 THEN 'win'
                WHEN '$player' IN(Players3.PlayerName, Players4.PlayerName) AND Scores.Score > 21 THEN 'loss'
                WHEN Scores.Score = 21 THEN 'draw'
                ELSE 'NA' 
                END as result,
        FROM Scores
        INNER JOIN Players Players1 ON Scores.Player1=Players1.PlayerID
        INNER JOIN Players Players2 ON Scores.Player2=Players2.PlayerID
        INNER JOIN Players Players3 ON Scores.Player3=Players3.PlayerID
        INNER JOIN Players Players4 ON Scores.Player4=Players4.PlayerID 
        WHERE Players1.PlayerName = '$player' OR Players2.PlayerName = '$player' OR Players3.PlayerName = '$player' OR Players4.PlayerName = '$player'
    ) AS SUBQUERY
    GROUP BY opp

Answer 1

它不是很漂亮，但由于MySQL缺少Pivot功能，你可以用一个内部查询来解决结果，该查询会分解谁扮演谁以及结果是什么。然后外部查询可以聚合这些结果。类似下面的东西对我有用，但是，再次，不漂亮：

select players.name as playerName, 
  opponents.name as opponentName, 
  SUM(CASE WHEN result = 'W'THEN 1 ELSE 0 END) AS win, 
  SUM(CASE WHEN result = 'L'THEN 1 ELSE 0 END) AS lose, 
  SUM(CASE WHEN result = 'D' THEN 1 ELSE 0 END) AS draw 
from  (
    select player1 as player, player3 as opponent, score, CASE WHEN score > 21 THEN 'W' WHEN score < 21 THEN 'L' ELSE 'D' END as result
    from scores
    union all
    select player1 as player, player4 as opponent, score, CASE WHEN score > 21 THEN 'W' WHEN score < 21 THEN 'L' ELSE 'D' END as result
    from scores
    union all
    select player2 as player, player3 as opponent, score, CASE WHEN score > 21 THEN 'W' WHEN score < 21 THEN 'L' ELSE 'D' END as result
    from scores
    union all
    select player2 as player, player4 as opponent, score, CASE WHEN score > 21 THEN 'W' WHEN score < 21 THEN 'L' ELSE 'D' END as result
    from scores
    -- now reverse result because opponents are being slotted into the player position
    union all
    select player3 as player, player1 as opponent, score, CASE WHEN score > 21 THEN 'L' WHEN score < 21 THEN 'W' ELSE 'D' END as result
    from scores
    union all
    select player4 as player, player1 as opponent, score, CASE WHEN score > 21 THEN 'L' WHEN score < 21 THEN 'W' ELSE 'D' END as result
    from scores
    union all
    select player3 as player, player2 as opponent, score, CASE WHEN score > 21 THEN 'L' WHEN score < 21 THEN 'W' ELSE 'D' END as result
    from scores
    union all
    select player4 as player, player2 as opponent, score, CASE WHEN score > 21 THEN 'L' WHEN score < 21 THEN 'W' ELSE 'D' END as result
    from scores
) resultsByPlayer
inner join players on players.playerId = resultsByPlayer.player
inner join players as opponents on opponents.playerId = resultsByPlayer.opponent
group by players.playerId, opponents.playerId

计算SQL中多列的值

1 个答案: