-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 01/28/07 08:36, John Meyer wrote: > Joris Dobbelsteen wrote: >>> CREATE TABLE attendance >>> ( >>> attendanceid serial primary key, >> Why you have this??? You already have (entered,timeperiod,studentid) >> that you can use, since that must be unique too. Try to avoid surrogate >> keys as much as possible (it really increases performance and >> ease-of-writing for complex queries! > > > Correct me if I am wrong, but wouldn't a simple number be a lot easier > to look up than a composite key? This is the great synthetic-vs-natural key debate. Sure, it's easier to write queries that join on a synthetic integer field. However, adding 3 extra fields to a few other tables is not onerous, and it adds useful information to the other tables, since (entered,timeperiod,studentid) are what *really* makes a record unique. Also, synthetic keys mean that you have to do more joins, since if you want to know about "entered" and table T_FOO, you'd have to join "attendance" to T_FOO. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFFvMH/S9HxQb37XmcRAoefAKDpf/6TG5WzP4nBIEcqVHE1dmb4/gCgxkZd 5fxfG4NoBR/Ul3fhqmpuTFQ= =g/F2 -----END PGP SIGNATURE-----
