Cannot Trap Specific ODBC Errors in OnError Property of a Form (KB 206175)

If you set the OnError property of a Access form to an event procedure, you cannot retrieve the description of an ODBC error in that procedure, and you also cannot trap a specific ODBC error. When an ODBC error occurs, the only information that is passed to the Error event procedure is the number of a generic error, such as 3146, which corresponds to the error message: ODBC-Call failed.

Cause

ODBC error messages normally consist of two components. The first component is error 3146, whose description is:

ODBC-Call failed

The server-specific error information is contained in the second component, from which you can retrieve an error number and a description such as:

[Microsoft][ODBC SQL Server Driver][SQL Server] <Server-specific error message> (#<error number>)

If you set the OnError property of a form to an event procedure, you can trap the number of the first component of the error, but you cannot trap the number of the second component. The server-specific information in the second part of the ODBC error appears on the screen after the code has finished running, unless you include the following line in the event procedure:

Response = acDataErrContinue

Resolution

Note: Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements.

You can create a Microsoft Visual Basic for Applications procedure that uses Data Access Objects (DAO) to update a RecordsetClone that is based on the form. This allows you to trap any error message that you receive.

DAO contains an Errors collection that you can use to trap the server-specific information in the second part of the ODBC error. When an ODBC error occurs, the first component is stored in the first element of the Errors collection, and the second component is stored in the second element.

The example in this article uses the BeforeUpdate event instead of the Error event to trap specific ODBC errors. To create a function that traps specific ODBC errors when the BeforeUpdate event of a form occurs, follow these steps:

  1. Create a blank desktop database.

  2. Link to the dbo_Accounts table in the AdventureWorks sample database in Microsoft SQL Server.

  3. Use the Form Wizard - Columnar layout to create a new form based on the accounts table.

  4. Save the form as frmAccounts.

  5. Create a new module, and then type the following line in the Declarations section if that line is not already there:

    Option Explicit

  6. Type or paste the following procedure into the module:

    Public Function SaveRecODBC(SRO_form As Form) As Boolean
    ' ***************************************************************
    ' Function: SaveRecODBC
    ' Purpose: Updates a form based on a linked ODBC table
    ' and traps any ODBC errors.
    ' Arguments: SRO_Form, which refers to the form.
    ' Returns: True if successful or False if an error occurs.
    ' ***************************************************************
    On Error GoTo SaveRecODBCErr
    Dim fld As Field, ctl As Control
    Dim errStored As Error
    Dim rc As DAO.Recordset
    
    ' Check to see if the record has changed.
    If SRO_form.Dirty Then
        Set rc = SRO_form.Recordset.Clone
        If SRO_form.NewRecord Then
            rc.AddNew
            For Each ctl In SRO_form.Controls
                ' Check to see if it is the type of control
                ' that has a ControlSource.
                If ctl.ControlType = acTextBox Or _
                    ctl.ControlType = acComboBox Or _
                    ctl.ControlType = acListBox Or _
                    ctl.ControlType = acCheckBox Then
                    ' Verify that a value exists in the ControlSource.
                    If ctl.Properties("ControlSource") <> "" Then
                        ' Loop through the fields collection in the
                        ' RecordsetClone. If you find a field name
                        ' that matches the ControlSource, update the
                        ' field. If not, skip the field. This is
                        ' necessary to account for calculated controls.
                        For Each fld In rc.Fields
                            ' Find the field and verify
                            ' that it is not Null.
                            ' If it is Null, don't add it.
                            If fld.Name = ctl.Properties("ControlSource") _
                            And Not IsNull(ctl) Then
                                fld.Value = ctl
                                ' Exit the For loop
                                ' if you have a match.
                                Exit For
                            End If
                        Next fld
                    End If ' End If ctl.Properties("ControlSource")
                End If ' End If ctl.controltype
            Next ctl
            rc.Update
        Else
            ' This is not a new record.
            ' Set the bookmark to synchronize the record in the
            ' RecordsetClone with the record in the form.
            rc.Bookmark = SRO_form.Bookmark
            rc.Edit
            For Each ctl In SRO_form.Controls
                ' Check to see if it is the type of control
                ' that has a ControlSource.
                If ctl.ControlType = acTextBox Or _
                    ctl.ControlType = acComboBox Or _
                    ctl.ControlType = acListBox Or _
                    ctl.ControlType = acCheckBox Then
                    ' Verify that a value exists in the
                    ' ControlSource.
                    If ctl.Properties("ControlSource") <> "" Then
                        ' Loop through the fields collection in the
                        ' RecordsetClone. If you find a field name
                        ' that matches the ControlSource, update the
                        ' field. If not, skip the field. This is
                        ' necessary to account for calcualted controls.
                        For Each fld In rc.Fields
                            ' Find the field and make sure that the
                            ' value has changed. If it has not
                            ' changed, do not perform the update.
                            If fld.Name = ctl.Properties("ControlSource") _
                                And fld.Value <> ctl And _
                                Not IsNull(fld.Value <> ctl) Then
                                fld.Value = ctl
                                ' Exit the For loop if you have a match.
                                Exit For
                            End If
                        Next fld
                    End If ' End If ctl.Properties("ControlSource")
                End If ' End If ctl.controltype
            Next ctl
            rc.Update
        End If ' End If SRO_form.NewRecord
    End If ' End If SRO_form.Dirty
    ' If function has executed successfully to this point then
    ' set its value to True and exit.
    SaveRecODBC = True
    
    Exit_SaveRecODBCErr:
        Exit Function
    
    SaveRecODBCErr:
    ' The function failed because of an ODBC error.
    ' Below are a list of some of the known error numbers.
    ' If you are not receiving an error in this list,
    ' add that error to the Select Case statement.
    For Each errStored In DBEngine.Errors
        Select Case errStored.Number
            Case 3146 ' No action -- standard ODBC--Call failed error.
            Case 2627 ' Error caused by duplicate value in primary key.
                MsgBox "You tried to enter a duplicate value in the Primary Key."
            Case 3621 ' No action -- standard ODBC command aborted error.
            Case 547 ' Foreign key constraint error.
                MsgBox "You violated a foreign key constraint."
            Case Else ' An error not accounted for in the Select Case ' statement.
                On Error GoTo 0
                Resume
        End Select
    Next errStored
    SaveRecODBC = False
    Resume Exit_SaveRecODBCErr
    
    End Function
    
  7. Save the module with a unique name and close the module window.

  8. Set the BeforeUpdate property of the frmAccounts form to the following event procedure:

    Private Sub Form_BeforeUpdate(Cancel As Integer)
    ' If you can save the changes to the record undo the changes on the form.
    If SaveRecODBC(Me) Then Me.Undo
    ' If this is a new record go to the last record on the form.
    If Me.NewRecord Then
        RunCommand acCmdRecordsGoToLast
    Else
        ' If you can't update the record, cancel the BeforeUpdate event.
        Cancel = -1
    End If
    End Sub
    
  9. On the Debug menu, click Compile <name of your database>

  10. If no errors occur, save the form.

  11. Open the frmAccounts form, and then add a new record or edit a record.

    When you make a change to a record, the record is saved when you move to a different record. If an ODBC error occurs, you see the custom message that is based on the server-specific error, and the generic "ODBC--call failed" message is trapped.

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