How To Save a DataSet Class as XML in .NET Framework SDK (301271)

SUMMARY

This document illustrates how to save relational data that is loaded into a DataSet class to a file as Extensible Markup Language (XML). This demonstrates the transition between relationally mapped data and XML data.

back to the top

Requirements

The following list outlines the recommended hardware, software, network infrastructure, and service packs that you will need:

• Microsoft Windows 2000 Professional, Windows 2000 Server, Windows 2000 Advanced Server, or Windows NT 4.0 Server
• Microsoft Visual Studio .NET

This article assumes that you are familiar with the following topics:

• XML terminology
• XML Schema Definition (XSD)
• Creating and reading an XML file

back to the top

How to Save a DataSet as XML

1. Open Visual Studio .NET.
2. Create a new Visual Basic .NET Console Application. You can go directly to the complete code listing or continue through these steps to build the application.
3. Use the Imports statement on the Data and Data.SQLClient namespaces so that you are not required to qualify declarations within those namespaces later in your code. You must use the Imports statement prior to any other declarations.

   Imports System.Data
   Imports System.Data.SqlClient
   					

4. Create a function named GetTitleAuthors that retrieves data from the SQL Server Pubs database. This sample assumes that you have SQL Server (with the Pubs database) installed on a local computer. This sample also assumes that you are using Integrated Authentication.

   Public Function GetTitleAuthors() As DataSet
   Dim MyConnection As SqlConnection = New SqlConnection("server=(local);database=pubs;Trusted_Connection=yes")
   Dim MyCommand1 As SqlDataAdapter = New SqlDataAdapter("select * from Authors", MyConnection)
   Dim MyCommand2 As SqlDataAdapter = New SqlDataAdapter("select * from Titles", MyConnection)
   
   Dim DS As New DataSet
   MyCommand1.Fill(DS, "Authors")
   MyCommand2.Fill(DS, "Titles")
   
   Return DS
   End Function
   					

5. In the Main module of Module1, declare a new DataSet, and call the GetTitleAuthors function to retrieve the DataSet:

           Dim m_SchemaFile As String
           m_SchemaFile = "testSchema.xml"
           Dim m_XmlFile As String
           m_XmlFile = "test.xml"
           
           Dim myDataSet as DataSet
           myDataSet = GetTitleAuthors
   					

6. To write out the schema that this DataSet created, use the WriteXmlSchema method of the DataSet class:

   myDataSet.WriteXmlSchema(m_SchemaFile)
   					

7. To write out the contents of the DataSet as XML, use a file name to call the WriteXml method of the DataSet class:

   myDataSet.WriteXml(m_XmlFile, XmlWriteMode.IgnoreSchema)
   					

8. Use the schema and the XML to re-create the dataset as necessary.
9. Build your project.
10. Make sure that the SQL Server is running.
11. Run the project, and then test the client-to-server communication.
12. Save and then close the project.

back to the top

Complete Code Listing

Visual Basic .NET Code

Imports System.Data
Imports System.Data.SqlClient

Module Module1

    Public Function GetTitleAuthors() As DataSet
        Dim MyConnection As SqlConnection = New SqlConnection("server=(local);database=pubs;Trusted_Connection=yes")
        Dim MyCommand1 As SqlDataAdapter = New SqlDataAdapter("select * from Authors", MyConnection)
        Dim MyCommand2 As SqlDataAdapter = New SqlDataAdapter("select * from Titles", MyConnection)

        Dim DS As New DataSet()
        MyCommand1.Fill(DS, "Authors")
        MyCommand2.Fill(DS, "Titles")

        Return DS
    End Function

    Sub Main()

        Dim m_SchemaFile As String
        m_SchemaFile = "testSchema.xml"
        Dim m_XmlFile As String
        m_XmlFile = "test.xml"

        Dim myDataSet As DataSet

        myDataSet = GetTitleAuthors()
        myDataSet.WriteXmlSchema(m_SchemaFile)
        myDataSet.WriteXml(m_XmlFile, XmlWriteMode.IgnoreSchema)



    End Sub

End Module
				

back to the top