SQL COUNT无法与将SELECT查询嵌套在LEFT外部联接中一起使用

Question

我需要一个Count才能在我的主选择中使用原始问题希望通过INTO现有的工作查询中的Group by添加一个Count查询

--- this join works ---
LEFT OUTER JOIN
WorkItemAssignedToUserFactvw AS IATUFact 
ON 
WI.WorkItemDimKey = IATUFact.WorkItemDimKey 
AND IATUFact.DeletedDate IS NULL 
--- this part below is in both queries ---
LEFT OUTER JOIN
UserDimvw AS AssignedToUser 
ON 
IATUFact.WorkItemAssignedToUser_UserDimKey = AssignedToUser.UserDimKey 

如果我将查询更改为具有选择语句的Left外部联接，那么我将遇到错误

LEFT OUTER JOIN
(
    SELECT
        WorkItemDimKey--,
        DateKey,
        --COUNT(WorkItemAssignedToUser_UserDimKey) AS Assignments
    FROM
        WorkItemAssignedToUserFactvw
    WHERE
        DeletedDate IS NULL
    GROUP BY
        WorkItemDimKey--,
        --DateKey
)
     IATUFact
        ON  WI.WorkItemDimKey = IATUFact.WorkItemDimKey

--- same query join as before except now it had an error 
LEFT OUTER JOIN
UserDimvw AS AssignedToUser 
ON 
IATUFact.WorkItemAssignedToUser_UserDimKey = AssignedToUser.UserDimKey 

错误：

消息207，级别16，状态1，行292无效的列名称'WorkItemAssignedToUser_UserDimKey'。

Answer 1

在您的SELECT中“使用”应该使用WorkItemAssignedToUser_UserDimKey来解决此问题，并将其添加到组中。

LEFT OUTER JOIN
(
    SELECT
        WorkItemAssignedToUser_UserDimKey,
        WorkItemDimKey,
        DateKey,
        COUNT(WorkItemAssignedToUser_UserDimKey) AS Assignments
    FROM
        WorkItemAssignedToUserFactvw
    WHERE
        DeletedDate IS NULL
    GROUP BY
        WorkItemAssignedToUser_UserDimKey,
        WorkItemDimKey,
        DateKey
)
     IATUFact
        ON  WI.WorkItemDimKey = IATUFact.WorkItemDimKey

--- same query join as before except now it had an error 
LEFT OUTER JOIN
UserDimvw AS AssignedToUser 
ON 
IATUFact.WorkItemAssignedToUser_UserDimKey = AssignedToUser.UserDimKey 

也许您已经注释掉了东西，看看是否是问题所在？