preventing duplicates

[Brian]

I have a group of invoices that have multiple items each.
What is the best way to prevent an items from a invoice
invoice from being loaded multiple times?

 

[Allen Browne]

Open the Northwind sample database, and take a look at the Orders and Order
Details tables.

Open the Relationship window (Tools | Relations), and see how they are
connected.

Open the Orders form in design view.
Right-click the edge of the subform, and choose properties.
On the Event tab of the Properties box, see how they have set the Master
Link Fields property to the name of the field in the Orders table, and the
Child Link Fields property to the name of the field in the related table.