透视基础:为什么我的聚合返回空值?

我这里有一个基本的支点问题,可能不会给你的古鲁带来任何麻烦:

我有一个很好用的SQL:

SELECT order_year, SUM(amount) AS Amount 
FROM dbo.mytable
GROUP BY order_year;

这会返回一种情况,比如:

2010 7000000
2007 8051222
2008 7099057
2009 13088790

现在,我想使用与此msdn文章中描述的相同的原则透视表: http://msdn.microsoft.com/en-us/library/ms177410.aspx

我试过这个:

SELECT 'Amount' AS Total_Amount_Sorted_By_Order_Year, 
[0], [1], [2], [3], [4]
FROM
(SELECT order_year, amount 
    FROM dbo.mytable ) AS SourceTable
PIVOT
(
SUM(amount)
FOR order_year IN ([0], [1], [2], [3], [4])
) AS PivotTable;

但这会返回一堆空值!:(

Amount NULL NULL NULL NULL NULL

我做错什么了?感谢您的帮助!

谢谢!