Check to see if part number already exists in database

Posted on 2014-11-23
Last Modified: 2014-11-28
I have a form which the user uses to enter a new part in the database.  The following code is supposed to halt the entry if the same part already exists.  Note that PART_NO is a text field.

But the code isn't working, the alert pops up even if the part does not exist already.

    'Code to check for existing part...
    Dim Answer As Variant
    Answer = DLookup("[PART_NO]", "tblParts", "[PART_NO] = '" & Me.txtPART_NO & "'")
    If Not IsNull(Answer) Then
        MsgBox "This part already exists in the database.  Please re-enter the details."
    End If

What am I doing wrong?
Question by:SteveL13
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 120

Expert Comment

by:Rey Obrero (Capricorn1)
ID: 40460662
try this codes instead

     If dcount("*", "tblParts", "[PART_NO] = '" & Me.txtPART_NO & "'")>0  Then
         MsgBox "This part already exists in the database.  Please re-enter the details."
     End If

Author Comment

ID: 40460678
Didn't work.  Sorry.

I am running the code from a command button on a form.  Here is the code with your suggestion in place...

Private Sub cmdCommitPartN_Click()
    'Code to check for existing part...
    If DCount("*", "tblParts", "[PART_NO] = '" & Me.txtPART_NO & "'") > 0 Then
        MsgBox "This part already exists in the database.  Please re-enter the details."
    End If
End Sub

Open in new window

LVL 48

Assisted Solution

by:Dale Fye (Access MVP)
Dale Fye (Access MVP) earned 250 total points
ID: 40460810
Both your DLOOKUP and Rey's DCOUNT syntax are correct, for what you have described.  You might try:
Dim strCriteria as string

strCriteria = "[PART_NO] = '" & Me.txtPART_NO & "'"
debug.print strCriteria
If dcount("*", "tblParts", strCriteria)>0  Then
    MsgBox "This part already exists in the database.  Please re-enter the details."
End If 

Open in new window

At least this way, you can actually see what is being tested, then you can open tblParts and confirm that the value is actually there.
LVL 50

Accepted Solution

Gustav Brock earned 250 total points
ID: 40460934
You may have better luck using the BeforeUpdate event of the form and its parameter Cancel:

     ' Code to check for existing part...
     Dim Answer As Variant
     Answer = DLookup("[PART_NO]", "tblParts", "[PART_NO] = '" & Me.txtPART_NO & "'")
     Cancel = Not IsNull(Answer)

     If Cancel = True Then
         MsgBox "This part already exists in the database.  Please re-enter the details."
     End If


Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Access custom database properties are useful for storing miscellaneous bits of information in a format that persists through database closing and reopening.  This article shows how to create and use them.
Did you know that more than 4 billion data records have been recorded as lost or stolen since 2013? It was a staggering number brought to our attention during last week’s ManageEngine webinar, where attendees received a comprehensive look at the ma…
In Microsoft Access, learn how to “cascade” or have the displayed data of one combo control depend upon what’s entered in another. Base the dependent combo on a query for its row source: Add a reference to the first combo on the form as criteria i…
Access reports are powerful and flexible. Learn how to create a query and then a grouped report using the wizard. Modify the report design after the wizard is done to make it look better. There will be another video to explain how to put the final p…

710 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question