Re: OMT->RDBMS

> I'm currently designing a system spec for a generic maufacturing system > using OMT. The A&D phase is complete and I've to oversee implementation > using Informix New-Era. What I'm wondering is how I should map my > functional details to an RDBMS framework. New-Era does support classes > I'know. Rumbaugh gives a lot of examples in his book so have a look there. You should try to separate class design from the DB design because the DB design is influenced by issues such as performance, access paths, etc. We use an intermediate layer between our business objects and the database so that changes to the database schema have minimal impact on the application. This layer is quite small so that it is easy to maintain. Basically, the object model maps directly to NewEra classes, and to design the database, take the object model and then do whatever you have to do i.e. denormalise, add redundancies, etc. Then write a thin layer which maps the two. > In particular I'm considering my link associations. should I implement > them in separate tables, or as fields in the table itself?? I would say that associations should be in the same table for performance reasons. Link attributes may be better in a separate table depending on the cardinality of the association. David W. Chan GO5 Ltd dwc@cix.compulink.co.uk