Q143263: HOWTO: Use an RDO Prepared Statement to Find a Single Record

Article: Q143263
Product(s): Microsoft Visual Basic for Windows
Version(s): 
Operating System(s): 
Keyword(s): kbRDO kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpDSVBDB
Last Modified: 13-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, version 6.0 
- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SUMMARY
=======

RDO does not have a FindFirst or a Seek method and in many cases as a programmer
you need to find out if a particular record exists or not. This sample uses an
RDO prepared statement to provide this kind of functionality. The following code
allows the user to type in a field they would like to search on (for instance,
OrderID, PONum, LastName), click on a command button and then see a message box
with the result of the query. This example will only find the first occurrence
of what you are searching for. You may also want to use a stored procedure once
you know that your query is working the way that you want it to. Keep in mind
that RDO is available in Visual Basic 4.0 32-bit and Visual Basic 5.0 Enterprise
Editions only.

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

Step-By-Step Example
--------------------

1. Start a new project in Visual Basic. Form1 is created by default. Add a
  CommandButton and a text box. Accept the default names for all.

2. Make sure a reference to the Microsoft Remote Data Object library has been
  established. In Visual Basic 4.0, you can establish the reference by clicking
  References from the Tools menu. In Visual Basic 5.0, click References from
  the Project menu.

3. Add the following code to the General Declarations section of Form1:

        Option Explicit
        Dim ps As rdoPreparedStatement
        ' Dim as rdoQuery    rdoquery replace PreparedStatement
        ' in VB5 and VB6
        Dim conn As rdoConnection
        Dim rs As rdoResultset

        Private Sub Form_Load()
            With rdoEnvironments(0)
                .CursorDriver = rdUseOdbc
           Set conn = .OpenConnection("", rdDriverNoPrompt, False, _
                "driver={SQL Server};
                server=Myserver;uid=MyUID;pwd=Mypwd;database=pubs")
            End With
            Set ps = conn.CreatePreparedStatement("", _
         '   CreateQuery replaces CreatePreparedStatement in VB5 and VB6
         '   Set ps = conn.CreateQuery("", _
                          "select au_lname from authors where au_lname = ?")
        End Sub

        Private Sub Command1_Click()
            ps.rdoParameters(0) = Text1.Text
            If rs Is Nothing Then
                Set rs = ps.OpenResultset(rdOpenKeyset)
            Else
                rs.Requery
            End If
            If Not rs.EOF Then
                Msgbox rs!au_lname
            Else
             Msgbox "No record match."
            End If
        End Sub

        Private Sub Form_Unload(Cancel As Integer)
            rs.Close
            ps.Close
            conn.Close
        End Sub

4. Make sure you have an appropriate ODBC data source, user ID, and password,
  then press F5 to run the program. Type your search criteria in Text1 (for
  example, "White"), and click the CommandButton. A message box will appear
  with either the record you are searching for if there is a match, or with a
  message "No record match" if there is no match.

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Keywords          : kbRDO kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpDSVBDB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVB500 kbVB600 kbVB400Search kbVB400
Issue type        : kbhowto

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