Question

如果我有一个如下所示的SQL表，我如何计算当前的连胜（并且按季节分组/重置连赢）。我想更新表并填写每条记录的条纹。

因此对于＃1，条纹将是“-1”，＃2将是“1”，＃3将是“2”，但是一旦我们下降到＃7，它将再次被重置为“1”。（+1表示“赢得1场比赛”，-1表示“失去1场比赛”等）

ID    team    date         Result    season     streak
1     76ers   2000-01-01   Loss      2000       Null
2     76ers   2000-01-05   Win       2000       Null
3     76ers   2000-01-08   Win       2000       Null
4     Lakers  2000-01-03   Loss      2000       Null
5     Lakers  2000-01-07   Loss      2000       Null
6     Lakers  2000-01-01   Win       2000       Null

7     76ers   2002-03-01   Win       2001       Null
8     76ers   2002-03-05   Win       2001       Null
9     76ers   2002-03-08   Loss      2001       Null
10    Lakers  2002-03-03   Loss      2001       Null
11    Lakers  2002-03-07   Loss      2001       Null
12    Lakers  2002-03-01   Win       2001       Null

Answer 1

对于每个游戏，计算与之前相同结果的游戏，这样就没有相反结果的游戏。将结果存储在临时表中：

CREATE TEMPORARY TABLE STREAK_TABLE
SELECT
    ID,
    (
        SELECT 1 + COUNT(*)                 -- Earlier games with the same result, team and season.
        FROM YOUR_TABLE T2
        WHERE
            T1.Result = T2.Result
            AND T1.team = T2.team
            AND T1.season = T2.season
            AND T1.date > T2.date
            AND NOT EXISTS (
                SELECT *                    -- The games in between, with the same team and season but opposite result.
                FROM YOUR_TABLE T3
                WHERE
                    T2.Result <> T3.Result
                    AND T1.team = T3.team
                    AND T1.season = T3.season
                    AND T3.date BETWEEN T2.date AND T1.date
            )
    ) S
FROM YOUR_TABLE T1

然后，更新原始表（并否定过程中的丢失条纹）：

UPDATE YOUR_TABLE
SET streak = (
    SELECT CASE Result WHEN 'Win' THEN S ELSE -S END
    FROM STREAK_TABLE
    WHERE STREAK_TABLE.ID = YOUR_TABLE.ID
)

最后，清理临时表：

DROP TABLE STREAK_TABLE

SQL计算输赢

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