Question

我的数据库中有2个表，如下所示：

以下是团队表：

id  tname          poule
1   ZF Eger        heren1A
2   Pro Recco      heren1A
3   Sintez Kazan   heren1A
4   Szolnoki VSE   heren1A
5   Sintez Kazan 2 heren1B
6   Szolnoki VSE 2 heren1B

以下是游戏表：

id date                hteam ateam hscore ascore gamefield poule   played
 1 2008-01-01 20:00:00     1     2      0      0 Veld 1    heren1A      0
 2 2008-01-01 20:00:00     3     4     10      8 Veld 2    heren1A      1

下面的代码在数据库上执行sql-query并输出联盟排名。

SELECT  poule AS Poule, 
        tname AS Team, 
        Sum(WG) AS WG,
        Sum(W) AS W,
        Sum(G) AS G,
        Sum(V) AS V, 
        SUM(DV) as DV,
        SUM(DT) AS DT,
        SUM(S) AS S,
        SUM(P) AS P 
FROM    ( 
            SELECT  hteam 
                    Team, 
                    IF(played = 1,1,0) WG, 
                    IF(hscore > ascore,1,0) W, 
                    IF(hscore = ascore,1,0) G, 
                    IF(hscore < ascore,1,0) V, 
                    hscore DV, 
                    ascore DT, 
                    hscore-ascore S, 
                    CASE WHEN hscore > ascore THEN 3 WHEN hscore = ascore THEN 1 ELSE 0 END P 
            FROM games 
            WHERE   played = 1 
                AND poule = ? OR played = 1 
                AND poule = ? 

            UNION ALL 
            SELECT  ateam, 
                    1, 
                    IF(hscore < ascore,1,0), 
                    IF(hscore = ascore,1,0), 
                    IF(hscore > ascore,1,0), 
                    ascore, 
                    hscore, 
                    ascore-hscore S, 
                    CASE WHEN hscore < ascore THEN 3 WHEN hscore = ascore THEN 1 ELSE 0 END 
            FROM games 
            WHERE   played = 1 
                AND poule = ? OR played = 1 
                AND poule = ?
            ) AS tot 
        JOIN teams t 
            ON tot.Team=t.id 
GROUP BY Team 
ORDER BY SUM(P) DESC, s DESC

我遇到的问题是：

没有参加比赛的球队没有被选中，但我仍然希望他们被选中，因为我需要显示完整的poule，即使没有比赛。如何更改我的查询，以便在没有比赛时也显示联赛积分？

Answer 1

您应该使用team作为锚点，LEFT JOIN使用您的统计信息：

SELECT  
    t.poule,
    t.tname AS Team,  
    IFNULL(Sum(WG), 0) AS WG,
    IFNULL(Sum(W) , 0) AS W,
    IFNULL(Sum(G) , 0) AS G,
    IFNULL(Sum(V) , 0) AS V, 
    IFNULL(SUM(DV), 0) as DV,
    IFNULL(SUM(DT), 0) AS DT,
    IFNULL(SUM(S) , 0) AS S,
    IFNULL(SUM(P) , 0) AS P 
FROM    teams t
        LEFT JOIN ( 
            SELECT  hteam 
                    Team, 
                    IF(played = 1,1,0) WG, 
                    IF(hscore > ascore,1,0) W, 
                    IF(hscore = ascore,1,0) G, 
                    IF(hscore < ascore,1,0) V, 
                    hscore DV, 
                    ascore DT, 
                    hscore-ascore S, 
                    CASE WHEN hscore > ascore THEN 3 WHEN hscore = ascore THEN 1 ELSE 0 END P 
            FROM games 
            WHERE   played = 1 
                AND poule = ? OR played = 1 
                AND poule = ? 

            UNION ALL 
            SELECT  ateam, 
                    1, 
                    IF(hscore < ascore,1,0), 
                    IF(hscore = ascore,1,0), 
                    IF(hscore > ascore,1,0), 
                    ascore, 
                    hscore, 
                    ascore-hscore S, 
                    CASE WHEN hscore < ascore THEN 3 WHEN hscore = ascore THEN 1 ELSE 0 END 
            FROM games 
            WHERE   played = 1 
                AND poule = ? OR played = 1 
                AND poule = ?
            ) AS tot ON tot.Team=t.id 

GROUP BY t.poule,t.tname 
ORDER BY SUM(P) DESC, s DESC

这样，所有球队都会被退回，包括那些没有统计数据的球队。

<强>结果*

heren1A Sintez Kazan    1   1   0   0   10  8   2   3
heren1A Szolnoki VSE    1   0   0   1   8   10  -2  0
heren1A ZF Eger         0   0   0   0   0   0   0   0
heren1A Pro Recco       0   0   0   0   0   0   0   0
heren1B Sintez Kazan 2  0   0   0   0   0   0   0   0
heren1B Szolnoki VSE 2  0   0   0   0   0   0   0   0

Answer 2

默认情况下，MySQL JOIN为INNER JOIN。您需要LEFT JOIN：

SELECT 
    poule AS Poule, 
    tname AS Team, 
    Sum(WG) AS WG, 
    Sum(W) AS W, 
    Sum(G) AS G, 
    Sum(V) AS V, 
    SUM(DV) as DV, 
    SUM(DT) AS DT, 
    SUM(S) AS S, 
    SUM(P) AS P 
FROM 
    (
        SELECT 
            hteam Team, 
            IF(played = 1, 1, 0) WG, 
            IF(hscore > ascore, 1, 0) W, 
            IF(hscore = ascore, 1, 0) G, 
            IF(hscore < ascore, 1, 0) V, 
            hscore DV, 
            ascore DT, 
            hscore - ascore S, 
            CASE WHEN hscore > ascore THEN 3 WHEN hscore = ascore THEN 1 ELSE 0 END P 
        FROM 
            games 
        WHERE 
            played = 1 
            AND poule = ? 
            OR played = 1 
            AND poule = ? 
        UNION ALL 
        SELECT 
            ateam, 
            1, 
            IF(hscore < ascore, 1, 0), 
            IF(hscore = ascore, 1, 0), 
            IF(hscore > ascore, 1, 0), 
            ascore, 
            hscore, 
            ascore - hscore S, 
            CASE WHEN hscore < ascore THEN 3 WHEN hscore = ascore THEN 1 ELSE 0 END 
        FROM 
            games 
        WHERE 
            played = 1 
            AND poule = ? 
            OR played = 1 
            AND poule = ?
    ) as tot 
    LEFT JOIN teams t ON tot.Team = t.id 
GROUP BY 
    Team 
ORDER BY 
    SUM(P) DESC, 
    s DESC

MySQL联赛表

2 个答案: