Many to many relationship

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Jack Corbett SSC Guru Points: 184394 More actions · Answer 1

I would create the "glue" tables because I think it would take less memory than storing each driver's data multiple times.

Christopher Mark SSC-Addicted Points: 417 More actions · Answer 2

thanks Jack

Is that the option that I should take whenever this problem arises

Jack Corbett SSC Guru Points: 184394 More actions · Answer 3

I can really only speak from a SQL Server perspective. If your application is data is like this:

Cars Trucks Drivers

------ ------- -------

Car1 Truck1 Driver1

Car2 Truck2 Driver2

And Driver1 can drive both cars and driver2 can drive car1 and both trucks, then yes I would do tables like:

car_drivers and truck_drivers

----------- -------------

Car1 - Driver1 Truck1 - Driver2

Car2 - Driver1 Truck2 - Driver2

Car2 - Driver2

Rather than a single Drivers table that has:

Car1 - Driver1

Car2 - Driver1

Car1 - Driver2

Truck1 - Driver2

Truck2 - Driver2

In SQL Server I would create a view that combines the driver data using a union query to get these results.