使用ADO连接数据库之后，可以参考一下代码查询数据并判断数据有效性

   sql = "SELECT 型号,出库标记 FROM main"

     mainRS.Open sql, maincomm

     If  mainRS.BOF = True  And  mainRS.EOF = True  Then

        MsgBox "库存为空！"

           outExcelApp.Workbooks(1).Close

                   outExcelApp.Quit 

                   Set mainRS = Nothing 

                   maincomm.Close

                   Set outputcomm=Nothing

                   MsgBox "退出导入过程！"

                   outputGrid.Clear

                   Exit Sub

         Else

                   mainRS.MoveFirst

                   Do  Until (mainRS.EOF)

                       If  mainRS("型号").Value = EType  Then

                               mainOfferHad = True

                               If  mainRS("出库标记").Value = 1  Then

                                       HadType = True

                               End If

                            End If

                            mainRS.MoveNext

                  Loop

         End If

    mainRS.Close