I've been googling for a long time now, reading lots of Normalization Tutorials, but haven't found an answer to my question....
The problem (in this question) is when I have something like a trip, where it has a start location and end location, but those locations are stored on a table and assigned an ID.
If I follow the normalization tutorials I end up with:
TripID, VehicleId, EndLocId, StartLocId, StartLocAddress, EndLocAddress
So if I normalize, I end up with these tables
1NF = UNF (no repeating groups)
2NF = 1NF (no partial dependency)
3NF (Separate Transitional Dependency)
Trip(TripId, VehicleId, StartLocId, EndLocId) TripStartLoc(StartLocId, StartAddress) TripEndLoc(EndLocId, EndLocAddress)
In my 3NF the last 2 tables will be exactly the same, so I want to use only one, a Location(LocId, LocAddress)
Trip(TripId, VehicleId, StartLocId, EndLocId) Location(LocId, LocAddress)
But I can't find any step that allows me to do this, I know I can do it because there's no point in maintaining 2 tables with repeated information... but how to justify? or is this step outside of Normalization? I just want 2 foreign keys in my trip table pointing to the location table, one for the starting point and one to the end point.
Thank you for your help