Re: update from select - Mailing list pgsql-sql

From Stephan Szabo
Subject Re: update from select
Date
Msg-id 20031029065413.C97497@megazone.bigpanda.com
Whole thread Raw
In response to update from select  (Gary Stainburn <gary.stainburn@ringways.co.uk>)
Responses Re: update from select  (Gary Stainburn <gary.stainburn@ringways.co.uk>)
List pgsql-sql
On Wed, 29 Oct 2003, Gary Stainburn wrote:

> Hi folks,
>
> don't know if it's cos of the 17 hours I've just worked (sympathy vote please)
> but I can't get this one worked out
>
> I've got table names with nid as name id field and nallowfollow flag.
> I've got a vehicles table with vowner pointing at nid and a vallowfollow
> field.
>
> How can I update nallowfollow from the appropriate vallowfollow flag?

If vehicles.vowner is unique, something like this maybe (using extensions
to sql)?
update names set nallowfollow=vehicles.vallowfollowfrom vehicles where vehicles.vowner=names.nid;

I think it'd be the follwoing in straight sql:
update names set nallowfollow=(select vallowfollow from vehicles where vehicles.vowner=names.nid);


If it's not unique, what do you do if there are two vehicles with the same
vowner and different values for vallowfollow?


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