Hello, I'm working on a new database and one of my tables includes various types of barcoding equipment. Each record should have its own unique Serial Number, so I made Serial Number my Primary Field for that table. I thought that, by default, the Primary Field always required unique values but I've just tried entering a duplicate S/N and it allowed the entry.
How can I make sure my Primary Field doesn't allow for the same value to be entered more than once?
