How do i allow duplicates in my primary key?

[ap_ple]

Flight_ID Passenger_ID Seat_Number Seat_Cost Seat_Class 1 3 j15 $112.00 Business 2 5 K16 $38.00 Economy 3 4 A12 $85.00 Economy 4 2 B05 $40.00 Economy 5 1 C08 $85.00 Economy 6 5 B12 $85.00 Economy 8 7 K17 $42.00 Economy 9 6 L25 $125.00 Business I need to be able to allow duplicated in the Flight_ID which is the primary key so i can allow more passengers to be able to "fly" on that flight :confused: iD

[Alsvha]

You can't have duplicate primary keys, it kind of defeats the entire purpose of having it as a primary key. A primary key needs to be unique. What you can do instead is make a combined primary key consisting of multiple columns or revisit whether you need/want that column as a primary key to begin with. Considering the snippet of your table you have posted, I would think that a combined key of Flight_ID and Passenger_ID (A specific passenger on a specific flight should all things equal be unique.) would be the best way to go.

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[Blue_Boy]

To allow adding multiple passagers on one flight then make combination of primary key with Flight_id and Passager_ID

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I Love T-SQL "Don't torture yourself,let the life to do it for you."

[Mycroft Holmes]

Your table design sucks - big time. You should have the following tables to get this data Flight - FlightNo Passenger - PassengerID Seat - SeatNo Cost - CostID Transaction TranID FlightNo PassengerID SeatNo CostID Your primary key Flight_ID is NOT the primary key for the transaction table as you are attempting to make it! Recommendation you REALLY need to get a book on data structuring before adventuring into this area, you will save yourself months of heartache. Even if you get this working for flight 1 (it is possible for 1 flight) as soon as you add another flight or another plane design or want to change the cost of a class of seats you are in trouble. GET A DESIGN BOOK - READ IT.

Never underestimate the power of human stupidity RAH

[Vinay Dornala]

Hi, Composite key on Fight_ID and Passenger_ID that might cause same problem in following scenario. If the same passenger let say 101 is booking fight 1001 for two different dates. 101 1001 $112.00 Business 5/3/2008 101 1001 $38.00 Business 7/3/2008 So best sol is to add identity column ( i. e TransactionID) in this case.