为什么 UNPIVOT 在兼容级别 80 DB 上工作？

Question

我正在尝试在兼容级别为 80 的 SQL Server 2008 SP3 数据库上使用 UNPIVOT 提取数据。这应该意味着 UNPIVOT 不起作用，但在我的情况下它在某些情况下起作用......

作品：

表单的独立 SELECT 查询：

SELECT...FROM...UNPIVOT...WHERE...GROUP BY

不起作用：

同一查询，在LEFT JOIN ()同一服务器内不同数据库上的其他表上。全部在兼容性级别 80。

我收到通常的错误消息：

Msg 325, Level 15, State 1, Line 165
Incorrect syntax near 'UNPIVOT'. You may need to set the compatibility level
of the current database to a higher value to enable this feature. See help for
the SET COMPATIBILITY_LEVEL option of ALTER DATABASE.

UNPIVOT解决方法似乎很麻烦，如果可能的话，我希望这个查询是独立的和可刷新的。如果我可以让查询独立工作，那么应该可以在JOIN.

问题：

为什么有时会这样？

在这些条件下如何实现UNPIVOT子查询JOIN？

Unpivot 子查询：（按要求...）

SELECT 
    YEAR(CAST('1-'+UnPiv.[Date] AS DATE)) "Year",
    MONTH(CAST('1-'+UnPiv.[Date] AS DATE)) "Month",
    CASE [Channel_Org]
        WHEN 'TPR' THEN 'ERP'
        ELSE [Channel_Org]
    END AS [Channel_Org],
    ISNULL(SUM(CASE WHEN [GL Desc] = 'EIP' AND 
        [OPEX_Group] = 'Postpaid SAC' THEN [Amount] END),0) "Post EIP",
    ISNULL(SUM(CASE WHEN [GL Desc] = 'EIP' AND
        [OPEX_Group] = 'Prepaid SAC' THEN [Amount] END),0) "Pre EIP",
    ISNULL(SUM(CASE WHEN [GL Desc] = 'EIP' AND
        [OPEX_Group] = 'SRC' THEN [Amount] END),0) "Upg EIP",
    ISNULL(SUM(CASE WHEN [GL Desc] = 'MDF (OEM)' AND
        [OPEX_Group] = 'Postpaid SAC' THEN [Amount] END),0) "Post MDF",
    ISNULL(SUM(CASE WHEN [GL Desc] = 'MDF (OEM)' AND
        [OPEX_Group] = 'Prepaid SAC' THEN [Amount] END),0) "Pre MDF",
    ISNULL(SUM(CASE WHEN [GL Desc] = 'MDF (OEM)' AND
        [OPEX_Group] = 'SRC' THEN [Amount] END),0) "Upg MDF"
FROM [Channel_Steering].[dbo].[AQ1_OPEX_View]
UNPIVOT (Amount FOR [Date] IN ( [Jan-14],
                                [Feb-14],
                                [Mar-14],
                                [Apr-14],
                                [May-14],
                                [Jun-14],
                                [Jul-14],
                                [Aug-14],
                                [Sep-14],
                                [Oct-14],
                                [Nov-14],
                                [Dec-14])) UnPiv
WHERE   (   [Channel_Org] IN ('Retail','TPR')
                AND
            [GL Desc] IN ('MDF (OEM)', 'EIP')
        )
GROUP BY
    [Channel_Org],
    YEAR(CAST('1-'+UnPiv.[Date] AS DATE)),
    MONTH(CAST('1-'+UnPiv.[Date] AS DATE))

Answer 1

答案在错误消息中：

您可能需要将当前数据库的兼容级别设置为更高的值才能启用此功能。

其中“当前数据库”表示上下文数据库 - 即执行查询的数据库，它不一定与查询中引用的数据库相同。例如，以下内容会产生错误消息：

USE AdventureWorks;
GO
ALTER DATABASE AdventureWorks 
SET COMPATIBILITY_LEVEL = 80;
GO
SELECT
    U.SystemInformationID,
    U.[Database Version],
    U.ColumnName,
    U.Value
FROM AdventureWorks.dbo.AWBuildVersion AS ABV
UNPIVOT 
(
    Value 
    FOR ColumnName IN 
        (
        VersionDate,
        ModifiedDate
        )
) AS U;

以下成功执行（假设tempdb兼容级别 > 80）：

USE AdventureWorks;
GO
ALTER DATABASE AdventureWorks 
SET COMPATIBILITY_LEVEL = 80;
GO
USE tempdb; -- Context database
GO
SELECT
    U.SystemInformationID,
    U.[Database Version],
    U.ColumnName,
    U.Value
FROM AdventureWorks.dbo.AWBuildVersion AS ABV -- Still references data in AW DB
UNPIVOT 
(
    Value 
    FOR ColumnName IN 
        (
        VersionDate,
        ModifiedDate
        )
) AS U;

您需要检查产生错误的连接的上下文数据库是什么。