MySQL 和 Dynamic Jasper 中的高级表旋转答案

【问题标题】：Advanced table pivoting in MySQL and Dynamic JasperMySQL 和 Dynamic Jasper 中的高级表旋转
【发布时间】：2020-10-29 13:11:43
【问题描述】：

我有一个 MySQL 表，它以时间表的方式存储我的课程。列是固定的，行是 id, day,class, classid, 1,2,3,4,5,6,7,8 这是我的表结构

_______________________________________________________________________________
| id | day | class | class_id |  1  |  2  |  3  |  4  |  5  |  6  |  7  |  8  |
|____|_____|_______|__________|_____|_____|_____|_____|_____|_____|_____|_____|
| 1  | Mon | FIA   |    1     | Eng | Che | Mat | Geo | Cre | Kis | His | Bio |
| 1  | Tue | FIA   |    1     | Geo | Cre | His | Che | His | Kis | Bio | Mat |
| 1  | Wed | FIA   |    1     | Mat | Eng | Geo | Geo | Cre | Bio | Cre | Bio |
| 1  | Thu | FIA   |    1     | Eng | Che | Mat | Eng | His | Kis | His | Geo |
| 1  | Fri | FIA   |    1     | Geo | Bio | Eng | Geo | Che | Mat | His | Bio |
| 1  | Mon | FIB   |    1     | Cre | Che | Mat | Eng | Cre | Kis | Eng | Che |
| 1  | Tue | FIB   |    1     | Eng | Che | Bio | Geo | Bio | Mat | His | Eng |
| 1  | Wed | FIB   |    1     | Eng | Eng | Mat | Mat | Cre | Eng | Geo | Bio |
| 1  | Thu | FIB   |    1     | Cre | Cre | Mat | Geo | Eng | Kis | Mat | Eng |
| 1  | Fri | FIB   |    1     | Mat | Che | Eng | Eng | Mat | Che | Mat | Bio |
| 1  | Mon | FIC   |    1     | Eng | Che | Che | Geo | Cre | Kis | His | Mat |
| 1  | Tue | FIC   |    1     | Che | Eng | Mat | His | Mat | Che | Che | Bio |
| 1  | Wed | FIC   |    1     | Cre | Che | His | Che | Bio | Kis | Bio | Mat |
| 1  | Thu | FIC   |    1     | Eng | Mat | Mat | Geo | Cre | Kis | His | Mat |
| 1  | Fri | FIC   |    1     | Eng | Che | His | Geo | Cre | Kis | His | Bio |
|____|_____|_______|__________|_____|_____|_____|_____|_____|_____|_____|_____|

我想做的是为所有课程创建一个摘要时间表。我正在使用动态 jasper 创建它，但最重要的是我得到了正确的查询。这是我期待实现的目标。

_____________________________________________________________________________________________________________________________________________________________________
|    |              Mon              |              Tue              |              Wed              |              Thu              |              Fri              |
|    | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
_____________________________________________________________________________________________________________________________________________________________________
|F1A |Eng|Che|Mat|Geo|Cre|Kis|His|Bio|Geo|Cre|His|Che|His|Kis|Bio|Mat|Mat|Eng|Geo|Geo|Cre|Bio|Cre|Bio|Eng|Che|Mat|Eng|His|Kis|His|Geo|Geo|Bio|Eng|Geo|Che|Mat|His|Bio|
|F1B |Cre|Che|Mat|Eng|Cre|Kis|Eng|Che|Eng|Che|Bio|Geo|Bio|Mat|His|Eng|Eng|Eng|Mat|Mat|Cre|Eng|Geo|Bio|Cre|Cre|Mat|Geo|Eng|Kis|Mat|Eng|Mat|Che|Eng|Eng|Mat|Che|Mat|Bio|
|F1C |Eng|Che|Che|Geo|Cre|Kis|His|Mat|Che|Eng|Mat|His|Mat|Che|Che|Bio|Cre|Che|His|Che|Bio|Kis|Bio|Mat|Eng|Mat|Mat|Geo|Cre|Kis|His|Mat|Eng|Che|His|Geo|Cre|Kis|His|Bio|
_____________________________________________________________________________________________________________________________________________________________________

您可以忽略带有天数的最顶部的列，我只需要一个查询，它将为我提供周一到周五每天的列 122345678。

【问题讨论】：

这看起来更像是电子表格而不是表格。为什么不规范化您的架构？
@Strawberry 这是其他人工作的延续，更改表结构会使我对整个项目必须做的工作量感到一团糟。
通过class加入5个表副本，过滤每个副本确定日期，选择需要的数据。
我怀疑这是值得的！无论如何，我无法提供进一步的建议，因为这是应用程序代码的问题，而且我不知道 jasper

标签： mysql sql pivot jasper-reports dynamic-jasper

【解决方案1】：

这可以在 SQL 中完成，尽管这可能不是完成这项工作的最佳工具，正如其他人已经评论的那样。

逻辑是使用条件聚合......和大量的打字。这是 3 列（col1、col2 和 col3）和两天（'Mon' 和 'Tue'）的示例：

select class,
    max(case when day = 'Mon' then col1 end) mon_1,
    max(case when day = 'Mon' then col2 end) mon_2,
    max(case when day = 'Mon' then col3 end) mon_3,
    max(case when day = 'Tue' then col1 end) tue_1,
    max(case when day = 'Tue' then col2 end) tue_2,
    max(case when day = 'Tue' then col3 end) tue_3
from mytable
group by class_id, class

然后您可以为其他日期和列展开相同的逻辑。

【讨论】：