Re: [MS_AccessPros] Invalid use of Null

 

Khalid-

You can test for empty entries like this (right after the On Error statement):

    If (Len(Me.cmbDestination & "") = 0) Or (Len(Me.ProductID & "") = 0 Then

        ' Take alternative action - don't try to lookup the rate

    Else

        varRate = DLookup( ….

        Me.Rate = NZ(varRate, 0)

    End If

John Viescas, Author

Effective SQL

SQL Queries for Mere Mortals 

Microsoft Access 2010 Inside Out

Microsoft Access 2007 Inside Out

Microsoft Access 2003 Inside Out

Building Microsoft Access Applications 

http://www.viescas.com/ 

(Paris, France)

On Apr 9, 2017, at 7:02 PM, khalidtanweerburrah@yahoo.com [MS_Access_Professionals] <MS_Access_Professionals@yahoogroups.com> wrote:

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Hi John,

I have a Form "New Cargo Collection Input" on its sub form "NewCargoCollectionInputsubform".

This sub form has a Text box "Rate" -->Standard, Decimal Places--> 2 on its On Got Focus event i 

have this code:

Private Sub Rate_GotFocus()

On Error Resume Next

    

    Dim varRate As Double

    varRate = DLookup("DestinationRate", "tblDestinationRates", _

              "Destination = '" & Me.cmbDestination & _

              "' AND ProductID = " & Me.ProductID & "")

              Me.Rate = Nz(varRate, 0)

End Sub

The issue is that if i omit the line "On Error Resume Next" i get an error message

Run-time error '94' Invalid use of Null

This happens when in "tblDestinationRates" there is no entry for Destination and ProductID

which is selected in sub form.

There is a form "Add New Destination Freight Rates" in which "DestinationRate" are entered for a 

specific Destination and ProductID when needed.

I need to know that is putting the line "On Error Resume Next" correct approach and logic ?

In this case, if there is no entry for Destination and ProductID. Text Box "Rate" shows 0.00 value 

and user enters value of his choice, else it picks the value from tblDestinationRates

Regards,

Khalid

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Posted by: John Viescas <johnv@msn.com>

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