NOT NULL Values for Dates

[The Archn00b]

Hi again

I have a text box with a date picker in a form. I need to create a piece of conditional logic in Visual Basic that is activated when the value in the form is not null. I can't so this in the same way as I would with a string which would be:

If Field <> "" Then
Statement
End If

Does any one know the equivalent for the Date datatype in Visual Basic?

Thanks for reading!

 

[pbaldy]

I'd probably use IsDate().

 

[The Archn00b]

I'd probably use IsDate().

Ah OK...

IsDate returns True if Expression is of the Date Data Type or can be converted to Date; otherwise, it returns False.
The Date data type holds both a date value and a time value. IsDate returns True if Expression represents a valid date, a valid time, or a valid date and time.

From http://msdn.microsoft.com/en-us/library/office/gg264241.aspx

If I was to change the default value to "null" in the property sheet, this wouldn't be seen as a date value and would represent the condition of the text box being blank? I'll try it.

 

[pbaldy]

Null should not be seen as a date, no.

 

[The Archn00b]

Doesn't work I'm afraid.

"Invalid Use of Null"

The only think i can think of is to use the default text box date value which is 01/01/0001 which would be very unlikely to be queried anyway. I'll try that.

 

[pbaldy]

How did you use it exactly?

?isdate(null)
False

 

[The Archn00b]

It refuses to even let me enter that date. It just changes it automatically to 01/01/2001, which is no good. Is there any way I can reference "default" as a value without putting in the actual default value in this case?

 

[The Archn00b]

How did you use it exactly?

?isdate(null)
False

Dim DateValue As Date
DateValue = DateBox.Value
Dim DateCheck As Boolean
DateCheck = IsDate(DateValue)
Dim DateBox_Parameter As String
If DateCheck = "True"  Then
STATEMENT
Else
STATEMENT
End If

 

[pbaldy]

The DateValue variable can't handle a Null, which is where your error comes from. It would have to be declared as Variant to take a Null. Here's code out of a db I have open that works fine with Nulls:

  If Not IsDate(Me.txtReqDate) Or Not IsDate(Me.txtReqTime) Then
    MsgBox "Must fill out requested date and time"
    Me.txtReqDate.SetFocus
    Exit Function
  End If

 

[pbaldy]

By the way, since there's a DateValue function, I wouldn't use that as a variable or object name.