Date: Thu, 26 Jun 2003 15:39:11 -0500
From: Bruno Wolff III <bruno@wolff.to>
To: Vinay <vinay@mdp.net>
Cc: pgsql-admin@postgresql.org
Subject: Re: Newbie question
Message-ID: <20030626203911.GA10461@wolff.to>
Mail-Followup-To: Vinay <vinay@mdp.net>, pgsql-admin@postgresql.org
References: <001c01c33c1d$843e0100$157a40c0@vinay>
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On Thu, Jun 26, 2003 at 15:59:55 -0400,
  Vinay <vinay@mdp.net> wrote:
> I have a very simple question regarding creating columns in a table
> 
> Can we create a column in a table in such a way that it will allow only certain length, nothing less or nothing more
> 
> here is an example
> 
> 
> create table test(column1 char(2));
> 
> will create table with column1 which will accept characters upto length two.
> 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]$'
);