Question

我正在使用Access（我知道JET SQL与T-SQL不同但是如果你在T-SQL中有答案我将尝试翻译它）并且我有以下内容：

表格部门名称和ID以及其他信息
表具有应用程序列表的应用程序以及它们是否可部署（布尔/位）
表连接DepartmentId和ApplicationId（n：n关系）

我试图了解每个部门可以部署多少个应用程序（简单），但也知道有多少个不可部署，因此完成百分比。（或至少类似（count（where deployable = true）/ count（*））

我真的不知道如何进行这样的查询。有什么想法吗？

Answer 1

（此答案是在Access 2010下开发和测试的。）

首先，我们需要一个查询，根据部门提供应用程序总数。易：

SELECT DepartmentId, Count(*) AS CountOfApplications
FROM ApplicationMapping
GROUP BY DepartmentId

说给我们

DepartmentId  CountOfApplications
------------  -------------------
           1                    4
           2                    1

您已经有了按部门计算可部署应用程序的查询，这可能看起来像这样

SELECT 
    am.DepartmentId, 
    Sum(IIf(a.Deployable,1,0)) AS CountOfDeployable
FROM
    ApplicationMapping AS am
    INNER JOIN
    Applications AS a
        ON am.ApplicationId = a.ApplicationId
GROUP BY DepartmentId

我们假设它给了我们

DepartmentId  CountOfDeployable
------------  -----------------
           1                  2
           2                  1

然后我们需要做的就是将这两个查询加在一起

SELECT 
    q1.DepartmentId,
    q2.CountOfDeployable / q1.CountOfApplications AS pctDeployable
FROM
    (
        SELECT DepartmentId, Count(*) AS CountOfApplications
        FROM ApplicationMapping
        GROUP BY DepartmentId
    ) AS q1
    INNER JOIN
    (
        SELECT 
            am.DepartmentId, 
            Sum(IIf(a.Deployable,1,0)) AS CountOfDeployable
        FROM
            ApplicationMapping AS am
            INNER JOIN
            Applications AS a
                ON am.ApplicationId = a.ApplicationId
        GROUP BY DepartmentId
    ) AS q2
        ON q1.DepartmentId = q2.DepartmentId

我们得到了

DepartmentId  pctDeployable
------------  -------------
           1            0.5
           2              1

编辑：

如果你想要一个包含所有Departments的列表，即使那些没有任何 Applications的那些，那么只需将整个前面的查询包装在另一个在[Department]表上进行外连接的查询中：

SELECT
    d.DepartmentId,
    d.DepartmentName,
    IIf(IsNull(calc.DepartmentId),0,calc.CountOfApplications) AS totalApplications,
    calc.pctDeployable
FROM
    Department AS d
    LEFT JOIN
    (
        SELECT 
            q1.DepartmentId,
            q1.CountOfApplications,
            q2.CountOfDeployable / q1.CountOfApplications AS pctDeployable
        FROM
            (
                SELECT DepartmentId, Count(*) AS CountOfApplications
                FROM ApplicationMapping
                GROUP BY DepartmentId
            ) AS q1
            INNER JOIN
            (
                SELECT 
                    am.DepartmentId, 
                    Sum(IIf(a.Deployable,1,0)) AS CountOfDeployable
                FROM
                    ApplicationMapping AS am
                    INNER JOIN
                    Applications AS a
                        ON am.ApplicationId = a.ApplicationId
                GROUP BY DepartmentId
            ) AS q2
                ON q1.DepartmentId = q2.DepartmentId
    ) AS calc
        ON d.DepartmentId = calc.DepartmentId

返回

DepartmentId  DepartmentName  totalApplications  pctDeployable
------------  --------------  -----------------  -------------
           1  Department1                     4            0.5
           2  Department2                     1              0
           3  Department3                     0

Answer 2

在这种情况下你必须使用联接 -

以下查询应该会给你想要的结果，但在Oracle数据库中。我不知道如何翻译成Access。

SELECT department_id,
       total_cnt,
       (deployable_cnt / total_cnt) * 100 deployable_perc,
       100 - (deployable_cnt / total_cnt) * 100 not_deployable_perc
FROM (SELECT dep.department_id,
             COUNT(*) total_cnt,
             SUM(CASE
                  WHEN app.deployable = 'Y' THEN
                  1
                  ELSE
                  0
                 END) deployable_cnt
       FROM department dep, applications app, applicationmapping appmap
      WHERE appmap.application_id = app.application_id
       and  appmap.department_id =  dep.department_id
 -- some other condition, if any
  GROUP BY dep.department_id)

SQL Group By选择％的值

2 个答案:

编辑：