Re: auto-increment column - Mailing list pgsql-general

From Robert Buckley
Subject Re: auto-increment column
Date
Msg-id 1317729939.30316.YahooMailNeo@web24104.mail.ird.yahoo.com
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In response to Re: auto-increment column  (Boszormenyi Zoltan <zb@cybertec.at>)
Responses Re: auto-increment column  (Boszormenyi Zoltan <zb@cybertec.at>)
Re: auto-increment column  (Joe Abbate <jma@freedomcircle.com>)
List pgsql-general
Thanks for the replies,

I have one question regarding this comment...

"You also need to add a DEFAULT expression and optionally
make the sequence owned by the column:"

What difference does it make if a table "owns" a sequence of not?...does this contraint the use of the sequence to ONLY that one table?

The sequence will only be used to auto-increment the id column in order to have an automatic primary key. Could I then somehow use the sequence for all tables which need this?

yours,

Rob




Von: Boszormenyi Zoltan <zb@cybertec.at>
An: pgsql-general@postgresql.org
Gesendet: 13:43 Dienstag, 4.Oktober 2011
Betreff: Re: [GENERAL] auto-increment column

2011-10-04 13:30 keltezéssel, Robert Buckley írta:
Hi,

I have a column in a table called hist_id with the datatype "integer". When I created the table I assigned this column the primary key constraint but didn´t make it an auto-increment column.

How could I do this to an the already existing column?

I have created the sequence with the following command but don´t know how to change the existing column to auto-increment.


$ create sequence hist_id_seq;

You also need to add a DEFAULT expression and optionally
make the sequence owned by the column:

ALTER TABLE tablename ALTER COLUMN hist_id SET DEFAULT nextval('hist_id_seq');
ALTER SEQUENCE hist_id_seq OWNED BY tablename.hist_id;

The "ALTER SEQUENCE ... OWNED BY ..." will make the sequence
automatically dropped if this column or table is dropped.


thanks for any help,

Rob


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Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
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