Change dataset to xml

Before we improve our web service, we practice our little xml conversion from dataset.
http://msdn.microsoft.com/en-us/library/58a18dwa.aspx


It's an web application. It doesn't have to be.

It prints out Hello There. but what it really does is making an xml file.

 We call a stored procedure. And change it to dataset ds. And the dataset is changed to XML string. Then it is written to a file.

 Result file looks like this.

 Note that null value doesn't make XML attribute, but when there is data, the attribute is created.

Now we develop this program a bit more.
(1) We want to save XML result to a string. (http://stackoverflow.com/questions/8384014/convert-dataset-to-xml)
(2) Then we want to select the first element from the XML string.

 Result looks like this.