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

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 6.0
• Microsoft Visual Basic Enterprise Edition for Windows, version 5.0
• Microsoft Visual Basic Enterprise Edition, 32-bit only, for Windows, version 4.0

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.

Keywords : kbRDO kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpVBDB
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Platform : WINDOWS
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