Question

我有一张表格，其中包含人员执行的操作列表。

在

SELECT COUNT(NICK) AS TOTAL, NICK, ACTION FROM ACTIONS2  GROUP BY ACTION,NICK ORDER BY NICK ASC, TOTAL DESC

它看起来像这样：

total   nick    action
13      0xlne   destroyed
5       0xlne   captured
5       0xlne   deployed
1       13key   destroyed
2       74pawel deployed
1       74pawel destroyed
1       74pawel captured

现在，我想多次动作破坏x75，捕获x500，部署x125等等，所以第一行应该看起来：（13 * 75 + 5 * 500 + 5 * 125 = 4100）

total   nick
4100    0xlne
75      13key

等等。有没有办法将这几种类型的操作与值相关联而不创建新表，并在乘法和求和之前加入它们？

Answer 1

这是使用CASE / WHEN

的问题

SELECT 
    SUM(CASE WHEN action='destroyed' THEN total*75 WHEN action='captured'   THEN total*500 ELSE total*125 END), nick 
FROM (SELECT COUNT(NICK) AS TOTAL, NICK, ACTION FROM ACTIONS2  GROUP BY ACTION,NICK ORDER BY NICK ASC, TOTAL DESC) AS nicks 
GROUP by nick;

作为脚注：通常大写用于SQL保留字，小写用于列/表名。

Answer 2

使用条件聚合并对加权值求和：

SELECT NICK, COUNT(*) AS totalAction
    COALESCE(SUM(ACTION='destroyed'),0)*75 +
    COALESCE(SUM(ACTION='capture'),0)*500 +
    COALESCE(SUM(ACTION='deploy'),0)*125
    as totalPoints
FROM ACTIONS2  
GROUP BY NICK 
ORDER BY NICK ASC, totalAction DESC

表达式

COALESCE(SUM(ACTION='destroyed'),0)*75

也可以写成

COUNT(CASE WHEN ACTION='destroyed' THEN 1 END)*75

或者

COUNT(ACTION='destroyed' OR NULL)*75

或许多其他方式。

有点不同的方法：

SELECT NICK, COUNT(*) AS totalAction,
    SUM(
        CASE ACTION
            WHEN 'destroyed' THEN 75
            WHEN 'capture'   THEN 500
            WHEN 'deploy'    THEN 125
            ELSE 0
        END
    ) as totalPoints
FROM ACTIONS2  
GROUP BY NICK 
ORDER BY NICK ASC, totalAction DESC

如何在MYSQL中用一个数字对特定值求和并乘以？

2 个答案: