Make A Date Null

Question

Can someone help me fix my code I am trying to put null in sql server through a function that is excepting _dtSWO.

If I set _dtSWO = Nothing it returns #12:00:00 AM# which throws an exception. The field is nullable in sql server I just want it to return a blank

Dim _swoDate As String = udSWOReceivedDateDateEdit.Text
        Dim _dtSWO As Date

        If _swoDate <> "" Then
            _dtSWO = Date.Parse(udSWOReceivedDateDateEdit.Text)
        Else
            'THIS DOESNT WORK
            _dtSWO = Nothing
        End If

Martin · Accepted Answer · 2010-09-02T16:06:38.543

4

You need to use a Nullable type. By default, Date does not except null (Nothing in VB.Net) as a value. Nullable types do accept null (Nothing).

    Dim _dtSWO As Nullable(Of Date)

    If String.IsNullOrEmpty(_swoDate) Then
        _dtSWO = Date.Parse(udSWOReceivedDateDateEdit.Text)
    Else
        _dtSWO = Nothing
    End If

Edited based on the comment.

edited Sep 02 '10 at 16:06

answered Sep 02 '10 at 15:59

Martin

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2

You may also want to catch the null string case; instead of comparing against an empty string literal, I'd use `String.IsNullOrEmpty()`. – tdammers Sep 02 '10 at 16:03

score 1 · Answer 2 · answered Sep 02 '10 at 16:00

1

Make it Nullable. Same kind of situation as your Nullable Integer question.

Dim _swoDate As String = udSWOReceivedDateDateEdit.Text
Dim _dtSWO As Date?

If _swoDate <> "" Then
    _dtSWO = Date.Parse(udSWOReceivedDateDateEdit.Text)
Else
    _dtSWO = Nothing
End If

answered Sep 02 '10 at 16:00

Larsenal

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The question mark is shorthand. Works in VB.NET although I generally don't see it used in many VB.NET examples online. – Larsenal Sep 02 '10 at 16:02
It was not valid syntax at first, but was added later: http://stackoverflow.com/questions/223844/history-of-vb-net-nullable-syntax – jball Sep 02 '10 at 16:04
I believe when nullable types were first introduced the `?` was not available in VB. However, at some point that ability was added. – Brian Gideon Sep 02 '10 at 16:09

Make A Date Null

2 Answers2