prevent duplicate records

[Guest]

I have table with following column name:
Region, BilltoNum, ShipToNum

Region and BillToNum are required field

You are not allowed to have Same Region, BillToNum, and ShiptoNum twice.
For example:
ATL, 111, 123
ATL, 111, 123
You can have Same Region and BillToNum.

However, problem is that you are not required to put ShipToNum because some
Region do not have ShipToNum. My questions is that, for regions with
ShipToNum, i would like to prevent duplicates when entering in the form.
I can't make all the fields primary key because, as stated, some do not have
ShipToNum.

Is there anyway to prevent duplicates for and when the user enters the
duplicates, i would like to have message box pop up saying " Duplicate
ShipTo" ?

Thank you!

 

[Guest]

Georgia:

Unfortunately, to do this you will most likely need to create code, as
Access (discussed in a recent post) does not handle Null values, in
multiple-field indexes, the way most of us (probably) think they should.

Sharkbyte