Re: Hierarchy of tables - Design problem

[Bob Field]

In the original post there was a reference to an Engines table which then linked into the Parts/Assemblies hierarchy. The Engines table is a possible choice for engine-specific parameters, although as you said you could have a whole bunch of combinations, and if they all involved the same base engine it would be nice to tag the base engine part with specific information like RPM and horsepower. It might be best to have a couple of ancillary tables here, one listing specific parameters and the other assigning parameter values to specific parts, i.e. engines.

Regarding combinations, yes you'll have lots, but you needn't have more combinations than you have previously manufactured, and surely that is a finite number. You add more parts and assemblies as you get requests for variations. You can start by copying an existing part, then copying assemblies to be altered, then adding&removing parts to suit.