Easy SQL to XML with LINQ and Visual Basic 2008
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by Richard Dudley
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Generating XML

As easy as LINQ has made data access, it has made working with XML even easier.  With LINQ, you don't need to create complex classes in order to serialize them.  Instead, XML is a native type in Visual Basic, so XML elements can be stated explicitly, intermixed with output commands to insert the correct values.

To create our XML document, we'll still need to instantiate an XML document, then add our elements, starting with the outermost (root) element.  Change Sub Main() to read as below:

Listing 5

Sub Main()
Dim _db As New ProductsDataContext
Dim _products = From p In _db.vProductModelCatalogDescriptions Select p
Dim _xml As New Xml.Linq.XDocument
Dim _xp As New XElement("Products")
_xml.Add(_xp)
_xml.Save("ProductCatalog.xml")
End Sub

Press F5 to run this code - it should execute just fine.  You can see the sample output in your bin/Debug folder (if necessary, remember to click the Show All Files button in the Solution Explorer).  We should have an XML declaration, and an empty Products element.

To add the details for each product, we need to loop through our collection of products and insert the proper values into each element.  We'll use another of the new features in VB9, and explicitly state XML elements in our code.  Change Sub Main() to read as below.  As you type the XML elements, notice that Visual Studio adds the closing element automatically.  Feel free to add more elements if you want to.   You can refer to the DBML file we created above for a list of available fields.  If you've ever used inline ASP.NET code on a web form, the shorthand <%= %> notation will be familiar to you.  Essentially, this shorthand means to insert (or print) the value contained inside the brackets.

Listing 6

Sub Main()
Dim _db As New ProductsDataContext
Dim _products = From p In _db.vProductModelCatalogDescriptions Select p
Dim _xml As New Xml.Linq.XDocument
Dim _xp As New XElement("Products")
For Each _p In _products
_xp.Add(<Product>
<ProductId><%= _p.ProductModelID %></ProductId>
<Name><%= _p.Name %></Name>
<Wheel><%= _p.Wheel %></Wheel>
<BikeFrame><%= _p.BikeFrame %></BikeFrame>
</Product>)
Next
_xml.Add(_xp)
_xml.Save("ProductCatalog.xml")
End Sub

Once you've made these changes, press F5, and check the output file after execution completes.  You should see all the products listed, with all the elements you specified.  If your example is not working properly, double check your syntax and make sure you entered it as show above.  The syntax inside the for each loop will seem strange at first, but keep in mind that XML is a native type in VB 9, so XML elements can be directly specified in our code.


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User Comments

Title: SQL or XML   
Name: Sunil
Date: 5/21/2012 2:05:53 AM
Comment:
Dear sir,
i want to create and access the Database using VB 2008.
which one i have to use SQL or XML.
Thank u.
Title: hi   
Name: titi
Date: 8/21/2008 8:48:59 AM
Comment:
very nice article

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