SQLServer XML Query

DECLARE @DOC XML ='
<books>
<book category="C#"> 
  <title language="en">C# in Depth</title> 
  <author>John Skeet</author> 
  <year>2010</year> 
  <price>62.30</price> 
</book> 
<book category="C#"> 
  <title language="cn">Effective C#</title> 
  <author>Bill Wagner</author> 
  <year>2010</year> 
  <price>49.00</price> 
</book>
<book category="MSSQL"> 
  <title language="cn">SQL2008 技術內幕</title> 
  <author>Itzik Ben-Gan</author> 
  <year>2010</year> 
  <price>90.20</price> 
</book>
<book category="javascipt">
<title language="cn">JavaScript權威指南</title>
<author>David Flanagan</author>
<year>2007</year> 
<price>87.20</price>
</book>
</books>
';
--查詢所有書籍的分類
SELECT 
	 T.C.value('@category','VARCHAR(16)')
FROM @DOC.nodes('/books/book') AS T (C);
--查詢所有C#書籍的名稱，作者，價格，年份
WITH B AS
(
	SELECT @DOC.query('//book[@category="C#"]') AS BookNode
)
SELECT 
	T.C.value('title[1]/@language','VARCHAR(32)') AS [language],
	T.C.value('title[1]','VARCHAR(32)') AS title,
	T.C.value('author[1]','VARCHAR(16)') AS author,
	T.C.value('year[1]','INT') AS [year],
	T.C.value('price[1]','DECIMAL(19,2)') AS price
FROM B
CROSS APPLY B.BookNode.nodes('/book') AS T (C);
--查詢所有書籍的語言和名稱
SELECT 
	T.C.value('@language[1]','varchar(56)') AS [Language],
	T.C.value('.','VARCHAR(56)') AS TITLE
FROM @DOC.nodes('/books/book/title') AS T (C);