Programming Visual Basic .NET

The DataSet’s XML Capabilities

The DataSet class has several methods for reading and writing data as XML, including:

GetXml

Returns a string containing an XML representation of the data in the DataSet object.

GetXmlSchema

Returns a string containing the XSD schema for the XML returned by the GetXml method.

WriteXml

Writes the XML representation of the data in the DataSet object to a Stream object, a file, a TextWriter object, or an XmlWriter object. This XML can either include or omit the corresponding XSD schema.

WriteXmlSchema

Writes the XSD schema for the DataSet to a Stream object, a file, a TextWriter object, or an XmlWriter object.

ReadXml

Reads the XML written by the WriteXml method.

ReadXmlSchema

Reads the XSD schema written by the WriteXmlSchema method.

Example 8-5 shows how to write a DataSet to a file as XML using the WriteXml method.

Example 8-5. Saving a DataSet to a file as XML

' Open a database connection. Dim strConnection As String = _ "Data Source=localhost;Initial Catalog=Northwind;" _ & "Integrated Security=True" Dim cn As SqlConnection = New SqlConnection(strConnection) cn.Open( ) ' Set up a data adapter object. Dim strSql As String = "SELECT * FROM Customers" _ & " WHERE CustomerID = 'GROSR'" Dim da As SqlDataAdapter = New SqlDataAdapter(strSql, cn) ' Load a data set. Dim ds As DataSet = New DataSet("MyDataSetName") da.Fill(ds, "Customers") ' Set up a new data adapter object. strSql = "SELECT Orders.*" _ & " FROM Customers, Orders" _ & " WHERE (Customers.CustomerID ...