-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 03/10/07 18:22, Christian Schröder wrote: > Peter Eisentraut wrote: [snip] > I know that it's always dangerous to quote the Wikipedia. Let me do it > anyway: "Attributes in tables in SQL database management systems can > optionally be designated as NULL. This indicates that the actual value > of the column is unknown _or not applicable_." > (http://en.wikipedia.org/wiki/Null_%28SQL%29) This is exactly what I > once learned about NULL values, and "not applicable" is exactly why I > use NULL values in my example. I've never heard of NULL meaning "not applicable", but only "unknown". To me, "not applicable" screams "denormalized". So, I'd put 1900-01-01 (or whatever is your application's epoch) in those date fields with NULL values, because that's their effective date. > > Regards, > Christian > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFF81kbS9HxQb37XmcRAkq/AJ0b6OkNtZZgNFOT/VGvqIWF2bI7DgCg4Emr lW+BWZseIkg/Vdf6fpK7dOI= =7jC/ -----END PGP SIGNATURE-----
