Mysql SQL中的IF/CASE语句

我真的很难找到这个问题的答案。我想写一个if或case语句来更改另一列中的值。如果列“check”为0，则列“points”也应为0

SELECT club_name, COALESCE(club_winner,0) AS 'check', COUNT(*) AS points,
    CASE 
    WHEN check = '0'
    THEN points = '0'
    ELSE check 
    END as Saleable
    FROM clubs c
    LEFT JOIN club_results cr ON c.club_id = cr.club_winner
    GROUP BY club_name ORDER BY points DESC

不能在case语句中“设置”列，可以返回值。将case语句视为变量列。将“0”返回为可销售的（或您希望命名的任何列）

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您可以选择仅计算与左连接匹配的线，如下所示：

SELECT
    club_name,
    COUNT(
        CASE WHEN
            club_winner IS NOT NULL
        THEN
            CR.id
        ELSE
            NULL
        END
    ) AS `points`
FROM
    clubs C
LEFT JOIN
    club_results CR ON C.club_id = CR.club_winner
GROUP BY
    C.club_id
ORDER BY
    points DESC 

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你的意思是“当check='0'然后'0'否则点以点结束”？你想在表中更新它，还是简单地显示它？这是MySQL还是Transact-SQL？你不能在select子句的后面重用以前的列别名。哎呀，@Donnie。“思想检查”是一个常规专栏（上面遗漏了）

SELECT
    club_name,
    COUNT(
        CASE WHEN
            club_winner IS NOT NULL
        THEN
            CR.id
        ELSE
            NULL
        END
    ) AS `points`
FROM
    clubs C
LEFT JOIN
    club_results CR ON C.club_id = CR.club_winner
GROUP BY
    C.club_id
ORDER BY
    points DESC