Am Freitag, 8. Oktober 2004 07:22 schrieb Miles Keaton:
What's the prevailing wisdom & best-practice advice about when to let a varchar (or any) column be NULL, and when to make it NOT NULL DEFAULT '' (or '0000-00-00' or whatever) - in PostgreSQL?
Briefly, you always do the first and never do the second.
Speaking of NULLs, what does the relational model ideal suggest for missing information?
a) no NULL at all; b) NULL and N/A;
I've read both, a) in "handling missing information without NULLs" articles and b) in Joe Celko's book ("Codd proposed two kind of missing information: NULL for unknown and N/A for not applicable").
-- dave
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