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来自「以电子书的形式收集了VB一些常见问题解决方法,可以很方便的查找自己需要解决的问题」· HTML 代码 · 共 26 行

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    <title>ADO &amp; NULL</title>
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      <h1>ADO &amp; NULL</h1>
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Posted by <a href="mailto:ariel_cy@usa.net">Ariel</a> on April 21, 1999 at 08:47:37:<p>
I have a procedure,I hope it can access from SQL with ADO,if a value of field<br>is NULL,then it's be space,but I can only get the value first,after the first,<br>I get NULL always.Why?<p>Global cn As New ADODB.Connection<br>Global quescmd As New ADODB.Command<br>Global quesrec As New ADODB.Recordset<p>Private Main()<br>    Dim parm As ADODB.Parameter<br>    Dim conn As String<br>    <br>    conn = "driver={SQL Server};server=ntserver1;uid=sa;pwd=;database=cbt"<br>    With cn<br>        .ConnectionString = conn<br>        .ConnectionTimeout = 10<br>        .Open<br>    End With<br>    <br>    Set quescmd = New ADODB.Command<br>    quescmd.ActiveConnection = cn<br>    With quescmd<br>        .CommandText = "select * from cbt_question where question_id=?"<br>        .CommandType = adCmdText<br>        .CommandTimeout = 15<br>    End With<br>    Set parm = New ADODB.Parameter<br>    With parm<br>        .Type = adChar<br>        .Size = 8<br>        .Direction = adParamInput<br>        quescmd.Parameters.Append parm<br>    End With<br>End Sub<p>Private Sub DispQues(quesid As String)<br>    Dim i As Integer<br>    Dim midstr As String<br>    <br>    quescmd.Parameters(0).Value = quesid<br>    Set quesrec = quescmd.Execute()<br>    <br>    If quesrec.EOF = True Then<br>        MsgBox "Not exist any question"<br>        Exit Sub<br>    End If<br>    <br>    QUESLABEL.Caption = quesrec!question_desc.GetChunk(200)   'All fields are Text in SQL<br>    For i=1 To 3<br>      if IsNull(quesrec.fields(i).getchunk(200)) Then    'here is correct,it have a value<br>          Label1(i).Caption=""<br>      Else<br>          Label1(i).Caption=quesrec.fields(i).getChunk(200)    'here prompt the value is NULL<br>      Endif<br>    Next i<br>End Sub
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