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Message-ID: <4f4c2a010710010824t7a2fbd59kb9102c879b389a5d@mail.gmail.com>
Date: Mon, 1 Oct 2007 11:24:00 -0400
From: "Jon Horsman" <horshaq@gmail.com>
To: "sql pgsql" <pgsql-sql@postgresql.org>
Subject: Populate unique column with default value
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Hey,

I'm updating the user table in our db to have a new column "username"
as follows.
ALTER TABLE usertable ADD COLUMN username varchar(64)
UPDATE usertable SET username='<extension of current row>' WHERE username ISNULL
ALTER TABLE usertable ALTER COLUMN username SET NOT NULL
ALTER TABLE usertable ADD CONSTRAINT usertable_username_key UNIQUE(username)

I want to essentially do what i have above but need to populate the
username field with some unique value so that the last ALTER will run.
 I have another column in this table that is unique, an phone
extension, and am hoping to use this as a default username.  Is there
an elegant way i can set the username to be the extension of the
current row or should i just write a little loop that goes threw and
populates my username with the users extension manually for each user
in my db and then run the last ALTER.

Thanks,

Jon.