There is no calculation that will return a unique value. Define the field as Text or Number, and set it to auto-enter a serial number. Import your data WITHOUT performing auto-enter options, and set the next serial number to the highest imported value + 1.
That did the job beautifully! ("**bleep** rookies!")
thanks a lot, I'm hoping to be able to save my data and over 20,000€ over 5 years in professional data management system!
not to mention the business opportunity I'm creating!