>Yes. I see, thank you. Now here's my next question if you could be so kind. I understand that you can't have duplicate records, but I thought you could do this: the index is on ProductName+RevisionNumber. In other words, I have a record for each product in a 'main' table. if there is a change to the product, it's Revision Number is incremented and a new record is added. Therefore, if you browsed for a particular product, you might see:
>ProductABC - Revision 0, ProductABC - Revision 1, ProductABC - Revision 2
>so, there are (in this example) three records where the product name is duplicated, but the Revision number is different. If I create an index on both fields, it still gives the "Uniqueness " error. Is there a better way to do what I'm trying to do? I have Product General information and submit, review, and approval dates in the 'main' file, and it works with three other tables that contain Technical information, Component or Formula information, and Material Safety Data Information....follow me?

PMFJI..The PK should something different. Product Name + Revision Number sounds like it is defined by the user, which is not a good PK. Look at the KB article on my web site that discusses Primary Keys.