如何修复where子句中的聚合？答案

【问题标题】：How to fix aggregate in where clause?如何修复where子句中的聚合？
【发布时间】：2017-04-19 22:16:12
【问题描述】：

消息 147，级别 15，状态 1，过程 vw_OverBudget，第 10 行 [批处理开始第 59 行]
聚合可能不会出现在 WHERE 子句中，除非它位于 HAVING 子句或选择列表中包含的子查询中，并且被聚合的列是外部引用。

代码：

CREATE VIEW vw_OverBudget 
AS
    SELECT
        p.projectName,
        SUM(a.costtodate) AS sumActivityCosts,
        p.fundedbudget
    FROM
        Project AS p
    FULL OUTER JOIN
        Activity a ON p.projectid = a.projectid  
    WHERE 
        a.activityId IS NULL
        AND p.projectid IS NOT NULL
        AND SUM(a.costtodate) > p.fundedbudget
    GROUP BY
        p.projectID

【问题讨论】：

标签： sql-server view

【解决方案1】：

此查询不需要full outer join。根据您的逻辑，left join 似乎是正确的：

Select p.projectName, sum(a.costtodate) AS sumActivityCosts,
       p.fundedbudget
From Project p left join
     Activity a 
     on p.projectid = a.projectid  
where a.activityId is null and p.projectid is not null 
Group By p.projectName, p.fundedbudget
having sum(a.costtodate) > p.fundedbudget;

但是，这对我来说没有意义。如果a.activityId 为空，那么最可能的原因是没有匹配。所以，我很确定你只想要一个没有 where 子句的 inner join：

Select p.projectName, sum(a.costtodate) AS sumActivityCosts,
       p.fundedbudget
From Project p inner join
     Activity a 
     on p.projectid = a.projectid
Group By p.projectName, p.fundedbudget
having sum(a.costtodate) > p.fundedbudget;

【讨论】：

使用内部连接，我看到你为什么在查看数据后使用这种类型的连接，我收到列“Project.projectName”的错误。它是说它是无效的，因为它不包含在聚合函数或分组依据中？
找到了解决办法，我只需要在group by中添加p.projectName即可。

【解决方案2】：

SQL SERVER 可能适用于其他数据库

group by 下缺少字段

Group By
    p.projectID
,p.fundedbudget  --- to add

添加

having sum >

在 where 子句中删除 sum

更新将是

    Create view vw_OverBudget AS
    Select 
        p.projectName,
        sum(a.costtodate) AS sumActivityCosts,
        p.fundedbudget
    From
        Project AS p
        full outer join Activity a ON p.projectid = a.projectid  
    WHERE 
        a.activityId is null and p.projectid is not null
    Group By
        p.projectID, p.fundedbudget
having SUM(a.costtodate) > p.fundedbudget
    go

【讨论】：