修改 SELECT 查询以创建堆积条形图

Posted 2023-05-09

【中文标题】修改 SELECT 查询以创建堆积条形图

【英文标题】：Modifying SELECT query to create Stacked Bar Chart

【发布时间】：2014-12-10 22:29:35

【问题描述】：

我有一个关于安置申请跟踪系统的查询，该系统显示每个学习计划安置和未安置的学生人数。即使查询返回所需的结果，我仍在努力创建一个 APEX 堆叠条形图。

查询：

 SELECT programme_name,
           SUM(CASE WHEN (cv_approval_date IS NOT NULL AND application_status_id <> 7) OR
                         application_status_id  IS NULL
                    THEN 1 ELSE 0 END) as Unplaced,
           SUM(CASE WHEN (cv_approval_date IS NOT NULL AND application_status_id <> 7) OR
                         application_status_id  IS NULL
                    THEN 0 ELSE 1 END) as Placed
    FROM programme LEFT JOIN
         student USING (programme_id) LEFT JOIN
         application USING (student_id)
    GROUP BY programme_name;

输出：

    PROGRAMME_NAME                                | PLACED   | UNPLACED
    BSc (Hons) Computer Science                   | 2        | 2 
    BSc (Hons) Computing and Games Development    | 1        | 0 
    BSc (Hons) Web Applications Development       | 0        | 1 
    BSc (Hons) Marine Biology and Coastal Ecology | 1        | 0

该图应该看起来与此类似 - x 轴是 Programme，y 轴是放置和未放置的学生人数：

http://ruepprich.files.wordpress.com/2011/03/stacked_bar.png?w=550&h=386

我该怎么做呢？任何帮助将不胜感激！

【参考方案1】：

在 Apex 中创建图表时，您可以点击“图表查询示例”查看适用于该图表类型的一些示例查询。

以堆积条形图为例，给出如下示例：

SELECT NULL LINK,
       ENAME LABEL,
       SAL "Salary",
       COMM "Commission"
FROM   EMP
ORDER  BY ENAME

在您的情况下，我认为您希望您的查询呈现以下格式：

SELECT NULL LINK,
       programme_name AS LABEL,
       SUM(...) AS "Unplaced",
       SUM(...) AS "Placed"
FROM ...