' update a data source through a DataAdapter' ' DA is the OleDbDataAdapter or SqlDataAdapter object' DT is the DataTable to be updated' if USETRANSACTIONS is True, all rows are updated, or none'' returns the number of affected records' or -1 if the update failedFunction UpdateDataAdapter(ByVal da As System.Data.IDbDataAdapter, _    ByVal dt As DataTable, ByVal useTransactions As Boolean) As Integer    Dim tr As System.Data.IDbTransaction    Dim affectedRows As Integer    ' we need a reference to a concrete DbDataAdapter object    Dim dda As System.Data.Common.DbDataAdapter = DirectCast(da, _        System.Data.Common.DbDataAdapter)    If useTransactions Then        ' get the connection object related to the DataAdapter        Dim cn As System.Data.IDbConnection = da.SelectCommand.Connection        ' open a transaction on that connection        tr = da.SelectCommand.Connection.BeginTransaction()        ' enroll all commands in that transaction        da.DeleteCommand.Transaction = tr        da.InsertCommand.Transaction = tr        da.UpdateCommand.Transaction = tr        ' we need an exception if an update conflict occurs        dda.ContinueUpdateOnError = False    Else        ' otherwise just ignore conflicts        dda.ContinueUpdateOnError = True    End If    Try        ' perform the update        affectedRows = dda.Update(dt)        ' if we get here, we can commit the transaction (if there is one)        If Not (tr Is Nothing) Then tr.Commit()    Catch ex As Exception        ' in this case we must rollback the transaction         ' (if there is one) and swallow the exception        If Not (tr Is Nothing) Then tr.Rollback()        affectedRows = -1    End Try    ' return the number of affected rows    Return affectedRowsEnd Function