（VS 2017）WPF/MVVM。如何回滚对项目集合的更改

我应该实现一个简单的过程，从映射到DB的数据收集中删除一些项（例如：车辆，ItemsDC实体容器的一部分）

我意识到DeleteObject（vei）似乎是立即提交的；所以，若引发异常并执行RollbackAll，则Vehicles集合已丢失一些项。 如何正确回滚更改

'DB Mapping
Public ItemsDC as ItemsDataContext

Sub DeleteVehicles()
  Try
    Dim qryV = From v In ItemsDC.Vehicles Where .... Select v
    If qryV.Count > 0 Then
      For Each vei In qryV
        ItemsDC.Vehicles.DeleteObject(vei)
      Next
    End If
    'Save changes to DB
    ItemsDC.SaveChanges(SaveOptions.AcceptAllChangesAfterSave)
  Catch ex As Exception
    'rollback changes
    RollbackAll()
  End Try 
End Sub

'RollbackAll, rebuilds collection from DB
Sub RollbackAll()
        Dim CString As String = ConfigurationManager.ConnectionStrings("ItemsDataContext").ConnectionString
        entityBuilder = New EntityConnectionStringBuilder(CString)
        Dim sqlBuilder = New SqlConnectionStringBuilder(entityBuilder.ProviderConnectionString)

        sqlBuilder.DataSource = DBName
        sqlBuilder.UserID = AppUser
        sqlBuilder.Password = AppPassword

        entityBuilder.ProviderConnectionString = sqlBuilder.ConnectionString
        ItemsDC = New RappCoaDataContext(entityBuilder.ConnectionString)
End Sub