Question

我需要在连接其他表并对它们进行计数计算时加入一个表。我顺便使用SQL Server 2008 R2。

当前状态 - 我有三个表MergedSessionsID，EventsSeparated和EventsDescriptions。

MergedSessionsID，这是我操纵数据的地方 - 会话主要是通过指定公司名称和会话时间（参见下面的数据示例）。

EventsSeparated表链接MergedSessionsID。基本上会话可以有一个或多个事件。

EventsDescription表包含事件的描述，例如这个和那个发生在用户身上。

我的目标是了解在一段时间内发生的事件总数。图表1是运行以下查询的结果。

但是，我还希望将旧数据与新数据进行比较，并查看事件数量的变化情况。因此，如图2所示，这就是我想象的结果 - 在2210年3月向PreCounter展示数据，在2210年4月向PostCounter展示数据。

实施此方法的最佳方法是什么？

SELECT E.[Event]
      ,COUNT(1) AS Counter
      ,ED.[Event Description]
FROM [ShipCompanies].[dbo].MergedSessionsID AS S
    INNER JOIN [ShipCompanies].dbo.EventsSeparated AS E
        ON S.ID = E.ID
    INNER JOIN [ShipCompanies].dbo.EventDescription AS ED
        ON E.[Event] = ED.[Unique ID]
WHERE S.Company = 'SuperSpaceShipOne'
  AND S.[Session Time] BETWEEN '2210-03-02' AND '2210-03-05'
GROUP BY E.[Event], ED.[Event Description]
ORDER BY E.[Event]


SELECT * FROM MergedSessionsID
ID   Company             Session Time
1   SuperSpaceShipOne   2210-03-05
2   SuperSpaceShipOne   2210-03-03 
3   SuperSpaceShipOne   2210-03-02 
4   SuperSpaceShipOne   2210-04-01
5   SuperSpaceShipOne   2210-04-02
6   SuperSpaceShipOne   2210-04-03


SELECT * FROM EventsSeparated
ID  Event
1   2000
2   2001
2   2002
3   2001
4   2002
5   2002
6   2002

SELECT * FROM EventDescription
Unique ID   Event Description
2000        'User Entered the Pod'
2001        'User Initiated Launching Sequence'
2002        'User Error encountered'

图表1.合并输出汇总表（我现在拥有的）

Event   Counter  Event Description
2000    1        'User Entered the Pod'
2001    2        'User Initiated Launching Sequence'
2002    1        'User Error encountered'

图表2.合并输出汇总表（我想要的内容）

Event  PreCounter   Event Description                  PostCounter
2000   1            'User Entered the Pod'              0
2001   2            'User Initiated Launching Sequence' 0
2002   1            'User Error encountered'            3

Answer 1

Select E.[Event]
    , Sum( Case 
           When S.[Session Time] Between '2210-03-02' And '2210-03-05' Then 1 
           Else 0 End ) As PreCounter
    , Sum( Case 
           When S.[Session Time] Between '2210-04-02' And '2210-04-05' Then 1 
           Else 0 End ) As PostCounter
      , ED.[Event Description]
From [ShipCompanies].[dbo].MergedSessionsID As S
    Join [ShipCompanies].dbo.EventsSeparated As E
        On S.ID = E.ID
    Join [ShipCompanies].dbo.EventDescription As ED
        On E.[Event] = ED.[Unique ID]
Where S.Company = 'SuperSpaceShipOne'
    And (
        S.[Session Time] Between '2210-03-02' And '2210-03-05'
        Or S.[Session Time] Between '2210-04-02' And '2210-04-05'
        )
Group By E.[Event], ED.[Event Description]
Order By E.[Event]

使用Count交叉连接表

1 个答案: