From: Lew <noone@lewscanon.com>
To: pgsql-sql@postgresql.org
Subject: Re: check constraint bug?
Date: Sat, 07 May 2011 08:52:21 -0400
Message-ID: <iq3fa3$b2o$1@news.albasani.net> (raw)
In-Reply-To: <BANLkTimt7GMbEgkRtLvKFy+kK8KDOnn2Og@mail.gmail.com>
References: <20110506060608.12bd24b0@dick.coachhouse>
<BANLkTimt7GMbEgkRtLvKFy+kK8KDOnn2Og@mail.gmail.com>
Scott Marlowe wrote:
> Tarlika Elisabeth Schmitz wrote:
>> I specified:
>>
>> ALTER TABLE h ADD CONSTRAINT val_h_stats
>> CHECK (NOT (sex = 'f') AND (stats IS NOT NULL));
>>
>> which was translated to:
>>
>> ALTER TABLE h ADD CONSTRAINT val_h_stats
>> CHECK (NOT sex = 'f'::bpchar AND stats IS NOT NULL);
> You need another level of parens:
>
> CHECK (NOT ((sex = 'f') AND (stats IS NOT NULL)));
Because NOT has higher precedence than AND.
<http://www.postgresql.org/docs/9.0/interactive/sql-syntax-lexical.html#SQL-PRECEDENCE;
Note that equals (=), IS and NOTNULL have higher precedence than NOT.
So the CHECK expression Scott indicated is equivalent to the parenthesis-minimal
CHECK ( NOT ( sex = 'f' AND stats IS NOT NULL ) )
or
CHECK ( sex != 'f' OR stats IS NULL )
--
Lew
Honi soit qui mal y pense.
http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg
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To: pgsql-sql@postgresql.org
Cc: noone@lewscanon.com
Subject: Re: check constraint bug?
In-Reply-To: <iq3fa3$b2o$1@news.albasani.net>
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