Question

我如何从此表中获得这些结果？我不完全确定它是否应该是一个联盟或加入。任何帮助将不胜感激。

表格

WorkOrderID   Activity      PlannedDuration    ActualDuration
11            Activity 1    4                  3.5
11            Activity 2    4                  3.6
11            Activity 3    4                  5
11            Activity 4    8                  7.2
11            Activity 5    6                  6
22            Activity 1    4                  3.5
22            Activity 2    4                  4
22            Activity 3    4                  3.9
22            Activity 4    8                  12
22            Activity 6    3                  3

结果

Activity        ActualDuration11    ActualDuration22 
Activity 1      3.5                 3.5 
Activity 2      3.6                 4 
Activity 3      5                   3.9 
Activity 4      7.2                 12

Answer 1

试试这个：

select foo.Activity, foo.ActualDuration as ActualDuration11, foobar.ActualDuration as ActualDuration22 
from (select Activity, ActualDuration from TABLENAME where WorkOrderID = 11) as foo 
join (Select Activity, ActualDuration from TABLENAME where WorkOrderID = 22) as foobar on (foo.Activity = foobar.Activity);

它使用join。你可能需要调整它（添加一个分组等等）以使它适用于你的实际数据库，但这应该是一个很好的框架。

在我的测试用例中，上面的查询返回了以下内容：

  Activity  | ActualDuration11 | ActualDuration12 
------------+------------------+-----------------
 Activity 1 |   3.5            |   3.5
 Activity 2 |   3.6            |   4
 Activity 3 |   5              |   3.9
(3 rows)

希望它有所帮助！

Answer 2

您可以通过加入同一个表中的两个SELECT语句并加入它们来实现此目的。查询可能如下所示：

SELECT * FROM
    (SELECT Activity, PlannedDuration, ActualDuration as ActualDuration11
    FROM YOUR_TABLE
    WHERE WorkOrderID = 11) t1
JOIN
    (SELECT Activity, PlannedDuration, ActualDuration as ActualDuration22
    FROM YOUR_TABLE
    WHERE WorkOrderID = 22) t2
        ON t1.Activity = t2.Activity;

SQL表自加入（或联盟？）麻烦

2 个答案: