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我有一个辩论比赛，我想找出哪支球队赢了和输了最多的辩论。我遇到的问题是参加辩论的两支球队的 id 在两个不同的列（hostid、visitid）中。

到目前为止，我有以下内容，这给了我想要的东西，但它只显示了访问 ID 数据。

    CREATE TABLE teams (
        id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
        name VARCHAR(255)
    ) DEFAULT CHARACTER SET utf8 ENGINE=InnoDB;

    CREATE TABLE debates (
        debateid INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
        debatedate DATE NOT NULL,
        hostid INT,
        visitid INT,
        winnerid INT
    ) DEFAULT CHARACTER SET utf8 ENGINE=InnoDB;

    INSERT INTO teams (id, name) VALUES
    (1,'team one'),
    (2,'team two'),
    (3,'team three'),
    (4,'team four'),
    (5,'team five'),
    (6,'team six');

    INSERT INTO debates (debateid, debatedate,hostid, visitid, winnerid ) VALUES
    (1,'2012-01-11', 1,2,1),
    (2,'2012-01-11', 3,4,4),
    (3,'2012-02-11', 5,6,5),
    (4,'2012-02-11', 1,4,1),
    (5,'2012-02-11', 2,5,5),
    (6,'2012-02-11', 3,6,3),
    (7,'2012-03-11', 6,1,1),
    (8,'2012-03-11', 5,2,5),
    (9,'2012-03-11', 3,4,4);

SELECT
    visitid AS id,
    t.name AS name,
    sum(visitid= deb.winnerid) as w,
    sum(visitid != deb.winnerid) as l
FROM debates AS deb
JOIN teams t ON t.id = deb.visitid
WHERE visitid != -1
AND debatedate < CURDATE( )
GROUP BY id
ORDER BY w DESC

结果

    -----------------------------------------
    |   ID  |   NAME        |   W   |   L   |
    |   4   |   team four   |   2   |   1   |
    |   5   |   team five   |   1   |   0   |
    |   1   |   team one    |   1   |   0   |
    |   6   |   team six    |   0   |   2   |
    |   2   |   team two    |   0   |   2   |
    -----------------------------------------

我如何结合这两列，我知道联合，但我想不出在这种情况下实现这一点的方法或者我应该使用什么方法？

如果我让它按预期工作，结果将如下所示，例如 hostid 或 visitid = winid

    -----------------------------------------
    |   ID  |   NAME        |   W   |   L   |
    |   1   |   team one    |   3   |   0   |
    |   5   |   team five   |   3   |   0   |       
    |   4   |   team four   |   2   |   1   |
    |   3   |   team three  |   1   |   2   |
    |   2   |   team two    |   0   |   3   |
    |   6   |   team six    |   0   |   3   |
    -----------------------------------------

例如见文件

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1 回答 1

1 
SELECT   t.id,
         t.name,
         SUM(t.id  = d.winnerid) AS w,
         SUM(t.id != d.winnerid) AS l
FROM     debates AS d
    JOIN teams   AS t ON t.id IN (d.hostid, d.visitid)
WHERE    d.visitid != -1  -- not sure what purpose this serves
     AND d.debatedate < CURDATE()
GROUP BY t.id
ORDER BY w DESC

在sqlfiddle上查看。

于 2013-11-01T14:54:07.190 回答