null = null

From: chester c young <chestercyoung(at)yahoo(dot)com>
To: pgsql-sql(at)postgresql(dot)org
Subject: null = null
Date: 2002-01-19 16:39:46
Message-ID: 20020119163946.8413.qmail@web12708.mail.yahoo.com
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the following took me by suprise:

egg=# select null=null;
?column?
----------
t

if this were true, for example, then only one null key could be in a
unique index, which is certainly not true.

i thought the philosphical idea behind null in SQL was you didn't know,
which can't have equivalence (as versus the pragmatic idea in C where
null is a dead end pointer, which can have equivalence). or have I
been too involved with my Oracle databases?

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