抱歉，如果事情真的很简单，我是个新手。我一直想把两张table合并起来，但做不成。正在尝试将雇员数添加到另一个表中。

SELECT [Training History].JobID,
    (
    SELECT Job.Department 
        FROM Job 
        WHERE [Training History].JobID = Job.JobID) AS Department, 
        SUM([Expenditure]) AS ExpenditureOfJob 
    FROM [Training History] 
    GROUP BY [Training History].JobID,
    (
    SELECT [Number of Employees] 
    FROM Q9r, 
    WHERE Q9r.JobID = [Training History].JobID
    )
;

这使我在上一个select语句中出错（请帮助：）
q9r表格代码为；

SELECT JobID, COUNT (*) AS [Number of Employees] FROM Employee GROUP BY JobID;
enter code here

也不能让它工作（这是我比较喜欢的方式，因为它可以在一个表中完成）

SELECT [Training History].JobID,(
       SELECT Job.Department 
       FROM Job 
       WHERE [Training History].JobID = Job.JobID) 
       AS Department, 
SUM([Expenditure]) AS ExpenditureOfJob 
     FROM [Training History] 
     GROUP BY [Training History].JobID,
(SELECT COUNT (*) AS [Number of Employees] 
     FROM Employee 
     GROUP BY JobID)
;

这也不行

SELECT [Training History].JobID,(SELECT Job.Department FROM Job WHERE [Training History].JobID = Job.JobID) AS Department, 
SUM([Expenditure]) AS ExpenditureOfJob FROM [Training History] GROUP BY [Training History].JobID,
(SELECT COUNT (*) AS [Number of Employees] 
     FROM Employee 
    WHERE [Training History].JobID = Employee.JobID
 GROUP BY JobID)
;