t-sql在事件表和日期范围之间的查询

Question

基于下表

id  Title   Date            Metadata  
------------------------------------
1   A       08/01/2010      M1
1   A       10/05/2010      M2
1   A       03/15/2011      M3
2   B       09/20/2010      M1
2   B       01/15/2011      M2
3   C       12/15/2010      M1

输入变量将是开始日期和结束日期。举个例子，

@startDate = '07/01/2010' 
@endDate = '06/30/2011'

如何生成以下输出？

Title  Jul-10  Aug-10 Sep-10 Oct-10 Nov-10  Dec-10 Jan-11 Feb-11 Mar-11 Apr-11 May-11 Jun-11
-------------------------------------------------------------------------------------------
A      Null    M1     Null    M2     Null   Null   Null    Null   M3     Null   Null   Null
B      Null    M1     Null    Null   Null   Null   M2      Null   Null   Null   Null   Null
C      Null    Null   Null    Null   Null   M1     Null    Null   Null   Null   Null   Null

Answer 1

您要查找的内容通常称为交叉表查询。如果您要问的是如何在给定静态列列表的情况下构建交叉表查询，您可以这样做：

Select Title
    , Min( Case When DatePart(mm, [Date]) = 7 And DatePart(yy, [Date]) = 2010 Then MetaData End ) As [Jul-10]
    , Min( Case When DatePart(mm, [Date]) = 8 And DatePart(yy, [Date]) = 2010 Then MetaData End ) As [Aug-10]   
    , Min( Case When DatePart(mm, [Date]) = 9 And DatePart(yy, [Date]) = 2010 Then MetaData End ) As [Sep-10]       
    ...
From Table
Where [Date] Between @StartDate And @EndDate
Group By Title

类似地，您可以按照断开的链接所建议的那样使用透视功能。但是，上面的解决方案和PIVOT功能都依赖于静态列声明。如果您想要的是列的动态列表(也称为动态交叉表)，那么您就超出了T-SQL的设计初衷。对于一些笨拙的动态SQL来说，这是可能的，但它很脆弱和笨重。相反，您应该在中间层组件中构建结果集，或者使用将构建交叉表结果的报告工具。

Answer 2

使用Pivot表..

一个简单的例子..

    USE AdventureWorks;
GO

SELECT DaysToManufacture, AVG(StandardCost) AS AverageCost 
FROM Production.Product
GROUP BY DaysToManufacture; 



DaysToManufacture  AverageCost  
0                  5.0885  
1                  223.88  
2                  359.1082  
4                  949.4105 

查询

    SELECT 'AverageCost' AS Cost_Sorted_By_Production_Days,   
[0], [1], [2], [3], [4]  
FROM  
(SELECT DaysToManufacture, StandardCost   
    FROM Production.Product) AS SourceTable  
PIVOT  
(  
AVG(StandardCost)  
FOR DaysToManufacture IN ([0], [1], [2], [3], [4]) 
) AS PivotTable;  

结果

Cost_Sorted_By_Production_Days   0                     1                     2                     3                     4

AverageCost                    5.0885                223.88                359.1082              NULL                  949.4105