DevGuru ADO Recordset::WillChangeRecordset Event

EVENT: Recordset::WillChangeRecordset

WillChangeRecordset (adReason, adStatus, pRecordset)

The WillChangeRecordset event can be fired before any pending change occurs in the contents of a Recordset. This can be due to a pending call to either the Open or Requery methods of the Recordset object.

In contrast, the RecordsetChangeComplete event can be fired after a change occurs in the Recordset.

An event is simply a subroutine that can be called automatically after a specific operation has occurred. This subroutine can contain any code that you need to run when the event occurs. The subroutine will only be called if it is included in your code.

There are three parameters passed to this event.

The adReason parameter is one of four of the EventReasonEnum constants that describe what pending operation caused this event to fire. Note that there is a total of fifteen of these constants, but only the following four can actually be used by this parameter.

EventReasonEnum Constants

Constant	Value	Description
adRsnClose	9	The Recordset has been closed
adRsnMove	2	The record pointer has been moved in the Recordset
adRsnRequery	11	The Recordset has been requeried
adRsnResynch	5	The Recordset has been resynchronized with the data source

The adStatus parameter is one of the EventStatusEnum constants that describes the current status of the event. If the action that triggered this event was successful, then the argument will be set to adStatusOK. If the pending operation cannot be cancelled, it will be set to adStatusCantDeny.

EventStatusEnum Constants

Constant	Value	Description
adStatusCancel	4	Cancels the operation that fired the event
adStatusCantDeny	3	Cannot cancel pending operation
adStatusErrorsOccurred	2	Indicates that warnings and/or errors occurred
adStatusOK	1	The operation that fired the event was successful
adStatusUnwantedEvent	5	The operation that generated the event cannot generate future events

The pRecordset parameter is the Recordset object to which this event applies.

Code (Visual Basic):
' Use the WithEvents keyword to designate that events
' can be handled by this Recordset object
Dim WithEvents objRecSet As ADODB.Recordset

' Note how the object name, objRecSet, is incorporated into the event Sub name
Private Sub objRecSet_WillChangeRecordset( adReason As ADODB.EventReasonEnum, _
   adStatus As ADODB.EventStatusEnum, _
   ByVal pRecordset As ADODB.Recordset )

' place any code you desire here, for example
If adReason = adRsnResynch Then
   adStatus = adStatusCancel
End If

End Sub