[dba-VB] Checking for NULL and empty strings

I tried these before, but they dont work when an empty string is passed:

    ' These two IsNull functions dont work when an empty string is passed,
so I used my own version above
    'Public Function IsNull2(ByVal strInput As String, ByVal strReplace As
String) As String
    '    If (strInput.Equals(System.DBNull.Value)) Then
    '        Return strReplace
    '    End If
    'End Function


    'Public Function IsNull3(ByVal strInput As String, ByVal strReplace As
String) As String
    '    If (IsDBNull(strInput)) Then
    '        Return strReplace
    '    End If
    'End Function


On 5/24/07, David Emerson <newsgrps at dalyn.co.nz> wrote:
>
> Thanks David,
>
> I originally had a similar syntax but was hoping that there was an
> shorter method.
>
> David
>
> At 25/05/2007, you wrote:
> >Here's a function I wrote (actually I wrote it for C#, but crossed it
> over
> >to vb.net)
> >
> >     Public Function IsNull(ByVal strInput As String, ByVal strReplace As
> >String) As String
> >         'This works like SQL server's IsNull, not VB/VBA. In VB/VBA it
> is
> >known as Nz()
> >         If (strInput Is Nothing) Then
> >             Return strReplace
> >         Else
> >             If strInput = "" Then
> >                 Return strReplace
> >             Else
> >                 Return strInput
> >             End If
> >         End If
> >     End Function
> >
> >
> >On 5/24/07, David Emerson <newsgrps at dalyn.co.nz> wrote:
> > >
> > > Group,
> > >
> > > I am wanting to test the value of a field from a data source.  If it
> > > is NULL or "" then do one thing, otherwise do another.  Here is
> > my vb.netcode:
> > >
> > >          If IsDBNull(Fields("MAddress2").Value) Or
> > > (Fields("MAddress2").Value = "") Then
> > >              Me.txtMailAddress.DataField = "=MAddress1"
> > >          Else
> > >              Me.txtMailAddress.DataField = "=MAddress1" + Chr(34) +
> > > ", " + Chr(34) + " + MAddress2"
> > >          End If
> > >
> > > The error message is "
> > >
> > > Operator '=' is not defined for type 'DBNull' and string "".
> > >
> > > What is the correct syntax for this?
> > >
> > >
> > > Regards
> > >
> > > David Emerson
> > > Dalyn Software Ltd
> > > Wellington, New Zealand
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> > >
> > >
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