Skip site navigation (1) Skip section navigation (2)

Re: Create unique field..

From: Jason Earl <jdearl(at)yahoo(dot)com>
To: "Williams, Travis L, NPONS" <tlw(at)att(dot)com>, pgsql-novice(at)postgresql(dot)org
Subject: Re: Create unique field..
Date: 2001-06-07 22:10:41
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-novice
One other thing you need to do is to make sure that
you don't actually put some other information into
that column.  For example, let's say that you have a
table defined like this:

processdata=# create sequence foo_seq;
processdata=# create table foo (id int default
nextval('foo_seq'), name text);

You might want to get a little fancier and make id a
primary key or something, but this gives you the
general idea.

Now if you were to insert a record where id was set
then your default value would get overwritten:

processdata=# insert into foo (id, name) values (100,
INSERT 6869711 1
processdata=# insert into foo (name) values ('Earl');
INSERT 6869712 1
processdata=# select * from foo
processdata-# ;
 id  | name  
 100 | Jason
   1 | Earl
(2 rows)

You will notice that the insert that I did where I did
not set id used the sequence without any problems. 
This is useful for cases where you *normally* want to
use the sequence but where there might be exceptions.

Hope this is helpful,


--- "Williams, Travis L, NPONS" <tlw(at)att(dot)com> wrote:
> All,
> 	I'm not sure if I'm on the right track here.. I
> want to create a
> column that is automatically filled in with a unique
> number when a row is
> created.. I thought that creating a sequence would
> do this.. and then
> creating a column with a default of
> nextval('seqname') but it isn't doing
> anything.. any help is appreciated...
> Thanks,
> Travis L. Williams
> ---------------------------(end of
> broadcast)---------------------------
> TIP 6: Have you searched our list archives?

Do You Yahoo!?
Get personalized email addresses from Yahoo! Mail - only $35 
a year!

In response to

pgsql-novice by date

Next:From: Sykora, DaleDate: 2001-06-07 22:39:17
Subject: 2 novice questions
Previous:From: Giorgio A.Date: 2001-06-07 21:49:55
Subject: Re: Create unique field..

Privacy Policy | About PostgreSQL
Copyright © 1996-2017 The PostgreSQL Global Development Group