From: Stephan Szabo <sszabo@megazone.bigpanda.com>
To: Ian Barwick <barwick@gmail.com>
Cc: Kenneth Gonsalves <lawgon@thenilgiris.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: replacing mysql enum
Date: Sat, 11 Dec 2004 07:47:51 -0800 (PST)
Message-ID: <20041211074227.J30051@megazone.bigpanda.com> (raw)
In-Reply-To: <1d581afe04121104255557ea@mail.gmail.com>
References: <04121110305520.21547@thenilgiris.com>
<1d581afe04121104255557ea@mail.gmail.com>
On Sat, 11 Dec 2004, Ian Barwick wrote:
> (Oddly enough, putting the NULL in the CHECK constraint seems
> to make the constraint worthless:
> test=> create table consttest (field varchar(2) check (field in
> (null, 'a','b','c')));
> CREATE TABLE
> test=> insert into consttest values ('xx');
> INSERT 408080 1
> test=> SELECT * from consttest ;
> field
> -------
> xx
> (1 row)
>
> Not sure what logic is driving this).
The way NULL is handled in IN (because it's effectively an equality
comparison). Unless I miss-remember the behavior, foo in (NULL, ...) can
never return false and constraints are satisified unless the search
condition returns false for some row. I think this means you need the
more verbose (field is null or field in ('a','b','c'))
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To: pgsql-sql@postgresql.org
Cc: sszabo@megazone.bigpanda.com, barwick@gmail.com, lawgon@thenilgiris.com
Subject: Re: replacing mysql enum
In-Reply-To: <20041211074227.J30051@megazone.bigpanda.com>
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