Prevent Duplicate Products or Services in an Order

In this video, I'm going to show you how to prevent your users from adding a duplicate product or service to a customer's order in your Microsoft Access database, using something called a Composite Key. 

Ramiro from Houston, Texas (a Platinum Member) asks: I run an auto detail shop. My database is pretty simple. We have about ten services that we provide. The problem is that sometimes one of my guys accidentally adds the same service twice, which should never happen. Is there a way to prevent this in the database?

Correction

In the video I mention that you cannot index Long Text fields. This used to be the case in older versions of Access. As of 2022, you can index Short Text, Long Text, Number, Date/Time, AutoNumber, Yes/No, and Hyperlink fields. You cannot index any of the field types that you shouldn't be using anyways: OLE Object, Calculated, Attachment. In older versions of Access you didn't used to be able to index Memo fields, which are now called Long Text fields, or Hyperlink fields. Honestly, I almost never index Long Text as that's going to be a real performance hit on your database. 

Members

Members will learn a different method to prevent duplicates. We'll use a little bit of VBA and the DCount function to check if the product is already on the order. If so, we'll ask the user if they want to add it or not. This also allows us to use a custom warning prompt instead of the default system message.

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