我有存在返回空值3个表(tblPreference
,tblCustomer
,tblCustomerPreference
),看起来像下面这样:SQL Server的动态支点当没有数据
tblPreference:
ID | Name | DefaultValue
(int PK) | (nvarchar(100)) | (nvarchar(100))
-------------------------------
1 | Preference1 | 1
2 | Preference2 | Yes
3 | Preference3 | 1
tblCustomer:
CustomerID | ...
(int PK)
--------------------
1 | ...
2 | ...
3 | ...
tblCustomerPreference:
ID | CustomerID | PreferenceID | Value
(int PK) | (int) | (int) | (nvarchar(100))
-------------------------------------------------------
1 | 1 | 1 | 0
2 | 1 | 2 | Yes
3 | 2 | 1 | 0
4 | 2 | 2 | No
我创建这个数据的一个支点所以这一切都在使用下面的存储过程,它会一直拉回来所有的喜好单行,如果找到一个客户特定值时,返回否则返回默认值:
CREATE PROCEDURE [dbo].[usp_GetCustomerPreferences] @CustomerID int AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from interfering with SELECT statements.
SET NOCOUNT ON;
DECLARE @PivotColumns nvarchar(max)
DECLARE @PivotColumnsSelectable nvarchar(max)
SELECT @PivotColumns = COALESCE(@PivotColumns + ',','') + QUOTENAME(Preference.Name),
@PivotColumnsSelectable = COALESCE(@PivotColumnsSelectable + ',' + Char(10),'') + Preference.Source + '.' + QUOTENAME(Preference.Name) + ' AS ' + QUOTENAME(Preference.Name)
FROM (SELECT [Name],
'PreferencePivot' AS [Source]
FROM [dbo].[tblPreference]) Preference
DECLARE @sqlText nvarchar(max)
SELECT @sqlText = 'SELECT ' + @PivotColumnsSelectable + '
FROM (SELECT tblPreference.Name AS PreferenceName,
CASE
WHEN tblCustomerPreference.Value IS NOT NULL THEN tblCustomerPreference.Value
ELSE tblPreference.DefaultValue
END AS Value,
@innerCustomerID AS CustomerID
FROM tblCustomerPreference
RIGHT JOIN tblPreference ON tblCustomerPreference.PreferenceID = tblPreference.ID
WHERE (tblCustomerPreference.CustomerID = @innerCustomerID OR tblCustomerPreference.ID IS NULL)) data
PIVOT (MAX(Value)
FOR PreferenceName IN (' + @PivotColumns + ')) PreferencePivot'
EXECUTE sp_executesql @sqlText, N'@innerCustomerID int', @CustomerID
END
的问题,我跑吧进入是当我查询CustomerID 1或2时,所有事情都按预期方式返回,所有值都按预期填充。但是,如果我查询CustomerID 3,它将返回一个NULL
为其他客户填充的任何偏好ID。如果我在没有PIVOT
表达式的情况下运行查询,它将返回按预期填充的所有首选项。只有当我穿透数据时,NULL
才会进入。我希望我错过了一些简单的事情,但我没有看到错误。
太棒了!像我预料的那样工作。考虑到它在pivoting之前创建临时表,我认为WHERE语句将在聚合中考虑。我将来必须记住这一点。 – 2009-11-13 14:25:08