PRB: DataEnvironment Recordset Requery Does Not Refresh Controls

• Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 6.0
• Microsoft Visual Studio 6.0

SYMPTOMS

If you have controls bound to a query built by the DataEnvironment and then call the underlying recordset's Requery method, your bound controls will still display data from the recordset prior to having called the Requery method. In short, you will still see your old data.

You may also see an error message stating:

"Error while trying to set current row."

RESOLUTION

• After you have re-queried the recordset, you must re-bind it.
  
  -or-



• Bind your controls to the recordset object rather than to the DataEnvironment. If you then call the Requery method on the recordset object, you see the up-to-date data in your bound controls.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

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



2. Add a DataEnvironment to your project.



3. Rename the connection "cnNWind" and use its property pages to use the Microsoft Jet OLE DB Provider to connect to the Northwind database (NWind.MDB) on your hard drive.



4. Add a command to the cnNWind connection. Rename the command "Customers," and use the SQL statement "SELECT CustomerID, City FROM Customers."



5. Drag-and-drop the CustomerID and City fields from the DataEnvironment onto your form.



6. Drag the Customers command from the DataEnvironment onto your form while holding down the right-mouse button. Select "Data Grid" from the available choices in the menu that appears when you release the right- mouse button.



7. Add two CommandButtons to your form. Name them cmdModifyData and cmdRequery.



8. Add the following code to your form:

   
         Private Sub Form_Load()
             cmdModifyData.Caption = "Modify Data"
             cmdRequery.Caption = "Requery"
         End Sub
   
         Private Sub ReBindMyControls()
             Set txtCustomerID.DataSource = DataEnvironment1
             Set txtCity.DataSource = DataEnvironment1
             Set DataGrid1.DataSource = DataEnvironment1
         End Sub
   
         Private Sub cmdModifyData_Click()
             Dim strSQL As String
             Dim strNewCity As String
             Dim intRecordsAffected As Integer
   
             strNewCity = InputBox("Enter a new value for the city")
             If strNewCity <> "" Then
                 strSQL = "UPDATE Customers " & _
                          "SET City = '" & strNewCity & "' " & _
                          "WHERE CustomerID = '" & _
                          DataEnvironment1.rsCustomers!CustomerID & "'"
                   DataEnvironment1.cnNWind.Execute strSQL, _
                                        IntRecordsAffected, adExecuteNoRecords
                 MsgBox intRecordsAffected & " record(s) affected"
             Else
                 MsgBox "No update performed"
             End If
         End Sub
   
         Private Sub cmdRequery_Click()
             DataEnvironment1.rsCustomers.Requery
             'ReBindMyControls
             MsgBox "Recordset reopened" & vbCrLf & _
                    "Current customer's city: " & _
                    DataEnvironment1.rsCustomers!City
         End Sub
    




9. Run the project.



10. Click on the button marked "Modify Data" to enter a new value for the current customer's city. The code will modify that row in the database without changing the row in the recordset.



11. Click on the button marked "Requery" to re-run the query. You will see a message box that says that the recordset has been re-opened and displays the value for the current customer's city in the recordset object. You will see the value that you entered in step 9 in this message box, but the textbox will still display the old value and the data in the grid will remain the same.



12. Exit the project by clicking on the "X" button in the upper-right corner of the form.



13. Modify the cmdRequery_Click event and un-comment the following line:

    
          ReBindMyControls
     




14. Re-run the project.



15. Click on the button marked "Modify Data" to enter a new value for the current customer's city. The code will modify that row in the database without changing the row in the recordset.



16. Click on the button marked "Requery" to re-run the query. You will see a message box that says that the recordset has been re-opened and displays the value for the current customer's city in the recordset object. You will see the value that you entered in Step 9 in this message box. The grid and textbox will now display the new value.
    
    NOTE: You could also bind your controls to the recordset itself rather than to the DataEnvironment by placing the following code in the Form_Load event. If you use this method, you do not need to re-bind your controls:

    
          txtCustomerID.DataMember = ""
          Set txtCustomerID.DataSource = DataEnvironment1.rsCustomers
          txtCity.DataMember = ""
          Set txtCity.DataSource = DataEnvironment1.rsCustomers
          DataGrid1.DataMember = ""
          Set DataGrid1.DataSource = DataEnvironment1.rsCustomers
       

Additional query words: binding kbCtrl kbVS600 kbdse kbDSupport kbVBp kbDataBinding kbVBp600
kbCtrl kbDataEnv kbDatabase

Keywords : kbGrpVBDB
Version :
Platform : WINDOWS
Issue type : kbprb