Three examples are given to illustrate when it is necessary to create a surrogate key in place of the primary key of a connection.

Analyze the variations between the generic definitions of 2NF and 3NF and the main key-based definitions. Explain your thinking by providing an example?

Consider the following set of requirements for a Flight reservation database: We conduct numerous flights departing from and arriving at various airports. We maintain a record of airport codes and addresses. Here is our requirements: Each airline schedules many flights.  A flight may be shared among multiple airlines, and therefore the flights can be scheduled by many airlines.  When multiple airlines share the same flights, each flight can be scheduled by many airlines. The passenger capacity of each flight varies depending on the aircraft's size and can accommodate up to 220 passengers.  We collect and store essential information such as the passenger's ID, name, credit card, and mileage plan number. To account for fluctuating prices, we must save the total cost at the time of booking as prices are subject to change. Every booking must be assigned to precisely one flight and be associated with at least one passenger. A newly introduced flight does not have any existing bookings.…

Specifically, how does the primary key of a connection relate to the interdependencies among its other qualities in terms of their usefulness?