>> In your case it would be lpp_id as PK, and >> lpp_person_id,lpp_language_id as unique constraint >> >> Thanks, >> Anton
Is there a reason to do it the way you suggest? Regards, Jorge Maldonado On Tue, Jul 23, 2013 at 5:02 PM, Anton Gavazuk <antongava...@gmail.com>wrote: > Hi Jorge, > > In your case it would be lpp_id as PK, and > lpp_person_id,lpp_language_id as unique constraint > > Thanks, > Anton > > On Jul 23, 2013, at 23:45, JORGE MALDONADO <jorgemal1...@gmail.com> wrote: > > > I have 2 tables, a parent (tbl_persons) and a child > (tbl_languages_per_person) as follows (a language table is also involved): > > > > ------------------ > > tbl_persons > > ------------------ > > * per_id > > * per_name > > * per_address > > > > -------------------------------------- > > tbl_languages_per_person > > -------------------------------------- > > * lpp_person_id > > * lpp_language_id > > * lpp_id > > > > As you can see, there is an obvious key in the child table which is > "lpp_person_id + lpp_language_id", but I also need the field "lpp_id" as a > unique key which is a field that contains a consecutive number of type > serial. > > > > My question is: what should I configure as the primary key, > "lpp_person_id + lpp_language_id" or "lpp_id"? > > Is the role of a primary key different from that of a unique index? > > > > With respect, > > Jorge Maldonado > > > > > > > > > > > > >