From: Tom Lane <tgl@sss.pgh.pa.us>
To: Bruno Wolff III <bruno@wolff.to>
Cc: Vinay <vinay@mdp.net>
Cc: pgsql-admin@postgresql.org
Subject: Re: Newbie question
Date: Thu, 26 Jun 2003 22:47:42 -0400
Message-ID: <23574.1056682062@sss.pgh.pa.us> (raw)
In-Reply-To: <20030626203911.GA10461@wolff.to>
References: <001c01c33c1d$843e0100$157a40c0@vinay>
<20030626203911.GA10461@wolff.to>
Bruno Wolff III <bruno@wolff.to> writes:
>> I want the column to accept the column value which is absolutely length of two.
> A char(2) will always have two characters (unless it is NULL). If you want
> to check for two nonblank characters or two letters or something like
> that use a check constraint.
> Some like:
> create table test (
> col1 char(2) constraint bad_length check (col1 ~ '^[a-zA-Z][a-zA-Z]$'
> );
The most obvious way to my mind is
check(length(rtrim(col1)) = 2)
if "length" is simply defined as "number of characters excluding
trailing blanks". If you want a more complex check then something
like Bruno's example will probably get the job done.
If you are going to apply a constraint like this then I'd counsel just
declaring the column as text --- making it char(2) simply means that
the system is applying an extra check that is redundant with your
constraint.
regards, tom lane
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To: pgsql-admin@postgresql.org
Cc: tgl@sss.pgh.pa.us, bruno@wolff.to, vinay@mdp.net
Subject: Re: Newbie question
In-Reply-To: <23574.1056682062@sss.pgh.pa.us>
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