使用UNION ALL在SQL Server中创建视图

Question

请考虑以下示例:

CREATE VIEW VW_YearlySales
AS

SELECT 2011 AS YearNo, ProductID, SUM(Amount) FROM InvoiceTable2011
UNION ALL
SELECT 2012 AS YearNo, ProductID, SUM(Amount) FROM InvoiceTable2012
UNION ALL
SELECT 2013 AS YearNo, ProductID, SUM(Amount) FROM InvoiceTable2013

GO

在InvoiceTable2013实际上并不存在并记录2013年第一发票时,我不想现在就创建它,它会自动创建.

谁能帮助我如何指定一个条件来验证表的存在UNION ALL？

非常感谢您的帮助.

Answer 1

不，据我所知，这是不可能的，你必须使用存储过程。在存储过程中，您可以验证表的存在性，并且根据该表的存在性，您可以更改 SQL。

编辑：

CREATE PROCEDURE GetYearlySales
AS

IF (EXISTS (SELECT *  
                 FROM INFORMATION_SCHEMA.TABLES  
                 WHERE TABLE_NAME = 'InvoiceTable2013')) 
BEGIN 

   SELECT 2011 AS YearNo, ProductID, SUM(Amount) FROM InvoiceTable2011 
   UNION ALL 
   SELECT 2012 AS YearNo, ProductID, SUM(Amount) FROM InvoiceTable2012 
   UNION ALL 
   SELECT 2013 AS YearNo, ProductID, SUM(Amount) FROM InvoiceTable2013

END
ELSE
BEGIN
   SELECT 2011 AS YearNo, ProductID, SUM(Amount) FROM InvoiceTable2011 
   UNION ALL 
   SELECT 2012 AS YearNo, ProductID, SUM(Amount) FROM InvoiceTable2012
END