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Q271621: HOWTO: Retrieve XML Data with a Template File from a VB Client

Article: Q271621
Product(s): Microsoft Visual Basic for Windows
Version(s): 2.6,2.7,3.0,4.0,6.0
Operating System(s): 
Keyword(s): kbXML kbGrpDSVBDB kbDSupport kbMDAC260 kbMSXML260 kbMSXML300 kbATM kbmdac270 kbMSXML400
Last Modified: 12-OCT-2001

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The information in this article applies to:

- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
- Microsoft Data Access Components versions 2.6, 2.7 
- Microsoft SQL Server 2000 (all editions) 
- Microsoft XML, versions 2.6, 3.0, 4.0 
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SUMMARY
=======

This sample in this article demonstrates how to retrieve an XML document from
SQL Server 2000 by using a template file that contains parameters. More
specifically, a query is issued against SQL Server 2000 by using an ADO 2.6
command stream. This query fetches the XML DataStream.

This sample reads the "products.xml" template file from disk, and sets the
command text for the ADODB.Command for the query to run. Properties to be set
for the ADODB.Command's Properties collection include:

  Base Path - establishes the location where the template and XSL files
  resides.

  Output Stream - designates where the resulting XML data stream is piped.

  XSL - transforms the XML document.

NOTE: Output Stream may be any object that supports an IStream or
ISequentialStream interface. Objects that support the IStream interfaces are the
ADODB.Stream, IIS5 Response object, and an MSXML DomDocument.

MORE INFORMATION
================

1. Create a new Standard EXE project in Visual Basic. Form1 is created by
  default.

2. On the Project menu, select Components, and then add a reference to both
  Microsoft Internet Controls and Microsoft ActiveX Data Objects 2.6.

3. Add a Web browser to the form, name it WebBrowser1, and then size it
  accordingly.

4. Add a frame to the form and place two option buttons in it. Name the first
  button optXSLYes with the caption XSL Yes, and name the second button
  optXSLNo with the caption XSL No.

5. Add two command buttons. Name the first button cmdTestIt with the caption
  Test, and name the second button cmdExitProgram with the caption Exit.

6. Paste the following Visual Basic code in the code window of the form:

  Option Explicit
  Const DBGUID_DEFAULT As String = "{C8B521FB-5CF3-11CE-ADE5-00AA0044773D}"
   
  Private Sub cmdExitProgram_Click()
      Unload Me
      End
  End Sub

  Private Sub cmdTestIt_Click()
      Dim cn As New ADODB.Connection
      Dim cmd As New ADODB.Command
      Dim cmdStream As New ADODB.Stream
      Dim cmdOutput As New ADODB.Stream
      Dim txtOutputFileName As String
      
      ' open the database connection 
      cn.Open "provider=sqloledb;data source=.;initial catalog=northwind;uid=sa;pwd="
      
      ' open the command stream that will eventually contain the templated query
      cmdStream.Open
      ' set the character set to ascii
      cmdStream.Charset = "ascii"
      ' set the command stream type to text, not binary.
      cmdStream.Type = adTypeText
      ' read the template file from disk into the command stream to execute
      cmdStream.LoadFromFile App.Path & "\products.xml"
      ' set the command connection
      Set cmd.ActiveConnection = cn
      ' set the command's command stream to hook the template query to the command you want to run.
      Set cmd.CommandStream = cmdStream
      ' set the command dialect
      cmd.Dialect = DBGUID_DEFAULT
      ' open the output stream to receive the results for the command execute.
      cmdOutput.Open
      ' set the base path for where the template file resides. 
      ' Currently, this must point to a file on disk. Remote templates via
      ' http://...template.xml" are not allowed.
      cmd.Properties("Base Path") = App.Path
      ' set up the output stream that will receive the output of the command execute.
      cmd.Properties("Output Stream") = cmdOutput
      
      ' set the XSL to process if the user requested the output to be fixed.
      If optXSLYes Then
          ' set the file name for the XSL: this inherits the "base path" setting
          cmd.Properties("XSL") = "products.xsl"
          ' set the file extension to ".htm", mainly so the Web browser displays
          ' set the output as a table.   Try with a ".xml" extension... what is displayed?
          txtOutputFileName = App.Path & "\queryout.htm"
      Else
          txtOutputFileName = App.Path & "\queryout.xml"
      End If

      ' execute the command stream with the settings specified above.
      cmd.Execute , , adExecuteStream
      ' position the stream back to the beginning: the "file position" in the 
      'stream will be at the end of the stream.  Writing to a stream will append
      'on the end and only while the output from the command execute generates.
      cmdOutput.Position = 0
      'save the output to a file, this is only needed to use the navigate on the Web browser control
      cmdOutput.SaveToFile txtOutputFileName, adSaveCreateOverWrite
      ' Navigate/display the results of the command executes.
      WebBrowser1.Navigate txtOutputFileName
      
      ' close and clean-up the objects used.
      cmdOutput.Close
      cmdStream.Close
      cn.Close
      
      Set cmdOutput = Nothing
      Set cmdStream = Nothing
      Set cmd = Nothing
      Set cn = Nothing
      
  End Sub

7. To create a template file, create a new text file, paste the following
  template into the file, and then save it with a name of products.xml:

  <?xml version='1.0' ?>          
  <root xmlns:sql="urn:schemas-microsoft-com:xml-sql">
      <sql:header>
          <sql:param name="ProdName">%</sql:param>
      </sql:header>
      <sql:query>
          SELECT      *
          FROM        Products
          WHERE       ProductName like '%' + @ProdName + '%'
          ORDER BY    ProductName                     
          FOR XML AUTO
      </sql:query>
  </root> 

8. As an option, create a file named products.xsl with the following code to
  transform the output:

  <?xml version='1.0' ?>          
  <xsl:stylesheet xmlns:xsl="http://www.w3.org/TR/WD-xsl">
      <xsl:template match="/">
          <html>
              <head>
                  <title>MSDN ADO Product Sample with SQL Server 2000 Features</title>
                  <base href="http://localhost/3tier/" />
              </head>
              <body>
                  <table border="0" cellPadding="1" cellSpacing="1"
                   width="100%" 
                   style="COLOR:black;FONT-FAMILY:Arial;FONT-SIZE:12pt.;FONT-WEIGHT:500">

                  <tr bgColor="#336699" align="center">
                      <TD><P ><STRONG><FONT color="white" size="2">Product ID:</FONT></STRONG></P></TD>
                      <TD><P ><STRONG><FONT color="white" size="2">Product Name:</FONT></STRONG></P></TD>
                      <TD><P ><STRONG><FONT color="white" size="2">Unit Price:</FONT></STRONG></P></TD>
                      <TD><P ><STRONG><FONT color="white" size="2">Units In Stock:</FONT></STRONG></P></TD>
                      <TD><P ><STRONG><FONT color="white" size="2">Restock Level:</FONT></STRONG></P></TD>
                      <TD><P ><FONT color="white" size="2"><STRONG>Units On Order:</STRONG></FONT></P></TD>
                  </tr>
                                  
                  <xsl:for-each select="root/Products">
                      <tr style="COLOR: black; FONT-FAMILY: Arial; FONT-SIZE: 0.8em; FONT-WEIGHT: 500">
                          <td bgColor="#F0F0F0"><xsl:value-of select="@ProductID"/></td>
                          <td bgColor="#F0F0F0"><xsl:value-of select="@ProductName"/></td>
                          <td bgColor="#F0F0F0"><xsl:value-of select="@UnitPrice"/></td>
                          <td bgColor="#F0F0F0"><xsl:value-of select="@UnitsInStock"/></td>
                          <td bgColor="#F0F0F0"><xsl:value-of select="@ReorderLevel"/></td>
                          <td bgColor="#F0F0F0"><xsl:value-of select="@UnitsOnOrder"/></td>
                      </tr>
                  </xsl:for-each>
                  </table>
              </body>
           </html>
      </xsl:template>
  </xsl:stylesheet>

REFERENCES
==========

For more information about SQL 2000, see SQL Server Books Online.

For more information on XML, see the following Microsoft Web site at:

  http://www.msdn.microsoft.com/xml/default.asp

or see the following site on the World Wide Web at:

  http://www.w3c.org/xml

Additional query words:

======================================================================
Keywords          : kbXML kbGrpDSVBDB kbDSupport kbMDAC260 kbMSXML260 kbMSXML300 kbATM kbmdac270 kbMSXML400 
Technology        : kbVBSearch kbSQLServSearch kbAudDeveloper kbZNotKeyword6 kbMSXMLSearch kbSQLServ2000Search kbZNotKeyword2 kbVB600Search kbVB600 kbMDACSearch kbMDAC260 kbSQLServ2000 kbMSXML260 kbMSXML300 kbMDAC270 kbMSXML400
Version           : :2.6,2.7,3.0,4.0,6.0
Issue type        : kbhowto

=============================================================================

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