| From: | David Garamond <lists(at)zara(dot)6(dot)isreserved(dot)com> |
|---|---|
| To: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
| Cc: | Miles Keaton <mileskeaton(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: when to use NULL and when to NOT NULL DEFAULT '' |
| Date: | 2004-10-08 11:12:35 |
| Message-ID: | 41667623.3080301@zara.6.isreserved.com |
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| Lists: | pgsql-general |
Peter Eisentraut wrote:
> 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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