????????????????????

???????磺?????NULL ?

????select ??????????????????????? from tb_stuInfo where ?????? is null

????4???????????????ε???

??????3??????????β????????е????????????????????Щ?????????

??????????????????????????п???γ?????

????1?????δ?

????2???????????

????3???ж???в?????

???????磺??????NULL???????

????select ??????????????????????? from tb_stuInfo where ?????? is not null

????5??????????????ж????????

????????? MSHFlexGrid1??????????????????????????????????????????"????null?"????????????ж?????null??? ??????????????____ISNULL ??????

?????????????????????????

???????????н????????￡??????????????

????select sum(Presentaddcash) as Presentaddcash??sum(Presentconsume) as Presentconsume?? _
????sum(Presentreturncash) as Presentreturncash??sum(Presentbalance)as Presentbalance?? _
????sum(Prioraddcash) as Prioraddcash  from  dayaccout_Info where  couutdate between'2012/9/17' and '2012/9/17'

?????????isnull???????ж?????NULL?????????

<SPAN style="FONT-SIZE: 18px"> '??д???????
        If Not IsNull(mrc.Fields("Prioraddcash").Value) Then
            TxtRemaincash.Text = mrc.Fields("Prioraddcash").Value
        Else
            TxtRemaincash.Text = 0
        End If</SPAN>

???????????NULL ????????????????????????NUll??????????0??

????????????????????????????? ?и????????????????????