From: Ilan Berci Date: 2009-08-13T05:54:23+09:00 Subject: Re: Destroying related objects doubt ... basic oop question Mike Stephens wrote: > Yet another reason for steering well clear of object-relational mappers. > > Stick with a proper relational database and everyone knows what's going > on, since we all worked that out 30 years ago. Actually, it wasn't worked out 30 years ago (I was there).. The OP is correct in stating that the relationship for the type of composition must be stated in the actual design/problem domain. Within UML(both 1 and 2), we represent aggregation of a resource with both a shared symbol and a containment symbol to represent the differences in ownership and what should happen if the container vanishes The same rules are specified in the database model through constraints.. no difference.. Ironically, the OPs question was very well phrased and had nothing at all to do with OR mappers.. ilan "defender of the OR mappers!" berci -- Posted via http://www.ruby-forum.com/.