<xml>
<Document>
<FileDetail>
<BookNumber>12345</BookNumber><BookAuthorLoop><Author name="John Doe"><Author name="Jane Doe"></DetailLoop>
</FileDetail>
</Document>

Insert into tblBook
Select *
From OpenXML
With (
BookNumber varchar(50) '/Document/FileDetail/BookNumber',
BookAuthor varchar(500) '/Document/FileDetail/BookAuthorLoop/Author/@name'
)

BookNumber  BookAuthor
1234            John Doe

Book Number         Book Author
1234                    John Doe, Jane Doe

DECLARE @xml XML
SET @xml = '<xml>
<Document>
<FileDetail>
<BookNumber>12345</BookNumber>
<BookAuthorLoop>
	<Author name="John Doe"/>
	<Author name="Jane Doe"/>
</BookAuthorLoop>
</FileDetail>
</Document>
</xml>'

SELECT a.c.value('(BookNumber/text())[1]', 'int')
	, b.c.value('(@name)[1]', 'varchar(30)')
FROM @xml.nodes('/xml/Document/FileDetail') AS a(c)
CROSS APPLY a.c.nodes('BookAuthorLoop/Author') AS b(c)

SET @xml = 'location of xml'

Insert into tblBook
 SELECT a.c.value('(BookNumber/text())[1]', 'int')
	, b.c.value('(@name)[1]', 'varchar(30)')
FROM @xml.nodes('/xml/Document/FileDetail') AS a(c)
CROSS APPLY a.c.nodes('BookAuthorLoop/Author') AS b(c)

BookNumber             Book Author
1234                       John Doe, Jane Doe