如何在子查询中使用 HAVING 作为 Select 语句的一部分

Question

我正在查询 return 今年有多少活动家按团队不止一次志愿服务；我让它作为一个独立的查询工作：

   SELECT Activists.team, COUNT(id) AS Activists
    FROM
    (
        SELECT e.id, v.team, 
        COUNT(CASE WHEN (e.status="Completed" AND right(e.date,2)="15") THEN e.id END) AS count
        FROM actiontable e
        LEFT JOIN persontable v ON v.id = e.id
        GROUP BY e.id, v.team
        HAVING (count > 1)
    ) AS Activists
    GROUP BY Activists.team;

但我不太明白如何让它在更长的 SELECT 语句中工作。我运行遇到的问题是，在 SELECT 语句中，我还有许多其他（更简单的）查询部分 return 团队的事情，例如：

COUNT(DISTINCT CASE WHEN v.WillCanvass = "X" THEN v.id END)

所以显然我不能为活动家查询 HAVING (count > 1) 部分，因为那样它会影响我的 SELECT 语句的所有其他部分——所以我需要上面的子查询只影响我正在处理的唯一部分。

我用示例模式创建了一个 SQL Fiddle 来帮助上面的查询工作——但理想的是得到一个看起来与此类似的输出，其中 Activists 子查询没有'影响 WillCanvass 列（即使我编造了下面的数字）：

Team    Activists   WillCanvass
Team A  2           2
Team B  8           5
Team C  7           3

希望这是有道理的 -- 谢谢！

编辑

我最好的结果是我想要的——尽管查询给了我错误——看起来像这样：

SELECT a.team as team,
    COUNT(v.*) as activists,
    SUM(CASE WHEN v.WillCanvass = "X" THEN 1 ELSE 0 END) as WillCanvass
FROM
persontable v
left join
(
    SELECT e.id, 
        v.team,
        v.WillCanvass,
        COUNT(*) as count
    FROM actiontable e
    LEFT JOIN persontable v ON v.id = e.id
    WHERE e.status="Completed" AND right(e.date,2)="15"
    GROUP BY e.id
    HAVING (count > 1)) as a 
        GROUP BY team;

SQL Fiddle here。

Answer 1

试试这个方法：

http://sqlfiddle.com/#!2/e186da/5

SELECT  v.team as team, 
        SUM(CASE WHEN (e.status="Completed" AND YEAR(e.date)="2015") THEN 1 ELSE 0 END) AS count
        FROM actiontable e
        LEFT JOIN persontable v ON v.id = e.id
        GROUP BY v.team
        HAVING (count > 1);


SELECT  v.team as team, 
        SUM(CASE WHEN (e.status="Completed" AND YEAR(e.date)="2015") THEN 1 ELSE 0 END) AS count,
        SUM(CASE WHEN (v.WillCanvass='X') THEN 1 ELSE 0 END) AS WillCanvass
        FROM actiontable e
        LEFT JOIN persontable v ON v.id = e.id
        GROUP BY v.team

Answer 2

不确定您要实现的目标。我首先获得具有正确标准的活动家名单，然后是 GROUP BY 团队。

SELECT a.team as team,
    COUNT(*) as activists,
    SUM(CASE WHEN a.WillCanvass = "X" THEN 1 ELSE 0 END) as WillCanvass
FROM (
    SELECT e.id, 
        v.team,
        v.WillCanvass,
        COUNT(*) as count
    FROM actiontable e
    LEFT JOIN persontable v ON v.id = e.id
    WHERE e.status="Completed" AND right(e.date,2)="15"
    GROUP BY e.id
    HAVING (count > 1)) as a 
GROUP BY team

Answer 3

我明白了 - 感谢您帮助我到达那里，但它与上面的任何内容都非常不同。我必须完全删除 HAVING 子句，以便 SELECT 语句的第一部分 (WillCanvass) 完全独立于它的 actiontable 部分：

SELECT a.team as team,
    COUNT(case when a.X > 1 then a.id else null end) as activists,
    SUM(CASE WHEN a.WillCanvass = "X" THEN 1 ELSE 0 END) as WillCanvass
FROM (
    SELECT v.id, 
        v.team,
        v.WillCanvass,
        COUNT(case when e.status="Completed" AND right(e.date,2)="15" then e.id else null end) as X
    FROM actiontable e
    RIGHT JOIN persontable v ON v.id = e.id
    GROUP BY v.id, v.team, v.WillCanvass
 ) as a 
GROUP BY team;

这是一个新的SQL Fiddle，看看它是如何工作的。

如何在子查询中使用 HAVING 作为 Select 语句的一部分

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