我是菜鸟,提一个简单问题

[Salif]

我的数据库是SQL Server,字段有id和end_date,请问在vb中如何判断数据库中的某个字段是否为空?
Dim m_lngId As Integer
Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
Dim rs As New ADODB.Recordset
Dim txtSQL As String
Dim MsgText As String

txtSQL = "select * from Event where id=" & m_lngId & "'and isnull(end_date) " '"
rs.Open txtSQL, cnMain, adOpenDynamic, adLockOptimistic
If Not rs.EOF Then
MsgBox "请先按开始", vbOKOnly + vbExclamation, "警告"
rs.Close
Else
rs.Close
Unload Me
End If
End Sub
这句sql错在哪里,最好能给出完整的sql语句并帮我看看程序还有哪些错！

[mingqing]

此时应大厦大厦大厦确保cnmain已打开，否则也会出错!

如果m_lngld为整型的数字变量，应为
txtSQL = "select * from Event where id=" & m_lngId & " and isnull(end_date) "

为字符变量应为
txtSQL = "select * from Event where id='" & m_lngId & "' and isnull(end_date)"

[道素]

txtSQL = "select * from Event where id=" & m_lngId & " and isnull(end_date) "
不要'号

[houtianxi]

isnull()函数可以判断

[arrow_gx]

txtSQL = "select * from Event where id=" & m_lngId & "'and isnull(end_date) " '"
rs.Open txtSQL, cnMain, adOpenDynamic, adLockOptimistic

第二句话错了，Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
或第一句 Dim m_lngId As Integer 放到第二句

txtSQL = "select * from Event where id=" & m_lngId & "'and end_data is null " '"

[arrow_gx]

我上面的SQL有点错，应该为

txtSQL = "select * from Event where id=" & m_lngId & "and end_data is null"

[Salif]

各位，end_date是字段名，它不是字符串形式，是不是要把end_date先赋给一个变量