Andreas Ntaflos <[EMAIL PROTECTED]> wrote: > On Friday 05 September 2008 21:57:30 Igor Tandetnik wrote: >> Andreas Ntaflos >>> Naturally a room cannot be identified without a building so it is a >>> weak entity (this seems to be the canonical example in all database >>> books I've seen). >>> >>> I'd like to auto-increment the ID numbers in both tables but as far >>> as I can see the AUTOINCREMENT keyword only works the way it is used >>> in the Building table. That is, only "INTEGER PRIMARY KEY >>> AUTOINCREMENT" is syntactically correct. >> >> Wait: if you want roomID to be autoincrement, then it's going to be >> unique (which, after all, is the point of autoincrement). Run it by >> my again: why can't you identify a room without a building? > > Well a room's existence depends on the building in which it is. > Different buildings can use the same room numbering scheme so in > order to know which room we are looking at we need to know its owning > building. Hence a room is a weak entity.
If you expect rooms in different buildings to have the same ID, then you can't use autoincrement for it anyway. > But it seems I misunderstood the point of AUTOINCREMENT. I am looking > for something like PostgreSQL's SERIAL data type [1] so when creating > new rooms I don't have to manually specify the roomID. Instead the > next possible roomID should be chosen automatically when INSERTing. But then you won't have two rooms with the same ID, and there won't be any problem making roomID a primary key. I don't see how you plan to have it both ways. Igor Tandetnik _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
