[dba-VB] Checking for NULL and empty strings

Thanks Charlotte, much appreciated.

David

At 26/05/2007, you wrote:
>Oops!  Make that the AndAlso operator <blush>.  That's what I get for
>multitasking!
>
>  If Not addrRow.IsMAddress2Null AndAlso addrRow.MAddress2.Trim.Length >
>0 Then
>
>Charlotte
>
>-----Original Message-----
>From: dba-vb-bounces at databaseadvisors.com
>[mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of Charlotte
>Foust
>Sent: Friday, May 25, 2007 7:52 AM
>To: dba-vb at databaseadvisors.com
>Subject: Re: [dba-VB] Checking for NULL and empty strings
>
>And once you have tested the IsNull, you can use the OrElse operator to
>check for an empty string like this:
>
>If Not addrRow.IsMAddress2Null OrElse addrRow.MAddress2.Trim.Length > 0
>Then
>
>The AndAlso and OrElse operators are a treasure because they only
>evaluate that part of the expression if the first part succeeds.
>
>Charlote Foust
>
>-----Original Message-----
>From: dba-vb-bounces at databaseadvisors.com
>[mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of Charlotte
>Foust
>Sent: Friday, May 25, 2007 7:32 AM
>To: dba-vb at databaseadvisors.com
>Subject: Re: [dba-VB] Checking for NULL and empty strings
>
>If you're using a typed dataset, string and some other data types have
>an Is<FieldName>Null property that you can test.  Cast the record as a
>row of the appropriate datatype to use it.  Then you should be able to
>use something like addrRow.IsMAddress2Null to check it.
>
>Charlotte Foust
>
>-----Original Message-----
>From: dba-vb-bounces at databaseadvisors.com
>[mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of David Emerson
>Sent: Thursday, May 24, 2007 5:52 PM
>To: dba-vb at databaseadvisors.com
>Subject: Re: [dba-VB] Checking for NULL and empty strings
>
>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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> > > dba-VB at databaseadvisors.com
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> > > http://www.databaseadvisors.com
> > >
> > >
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