From: | Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com> |
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To: | Sean Shanny <shannyconsulting(at)earthlink(dot)net> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: Need some help with crafting a query to do major update |
Date: | 2004-02-19 03:11:08 |
Message-ID: | 20040218190832.H38717@megazone.bigpanda.com |
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Thread: | |
Lists: | pgsql-sql |
On Wed, 18 Feb 2004, Sean Shanny wrote:
> To all,
>
> This is part of a data warehouse. Made the mistake of using a natural
> key in one of the fact tables. :-( The f_test_pageviews is a simple
> testing table while I work this out. The real table has an identical
> schema.
>
> I have built a mapping table, d_user, to allow the replacement of the
> text based (32 characters wide) subscriber_key in f_test_pageviews with
> an int4 mapping key. I need to replace all of the
> f_test_pageviews.subscriber_key values with the d_user.id value putting
> it in f_test_pageviews.sub_key column.
>
> I have tried this sql:
>
> update f_test_pageviews set sub_key = t2.id from f_test_pageviews t1,
> d_user t2 where t1.subscriber_key = t2.user_id;
I don't think the above does what you want because I don't think you meant
to be joining f_test_pageviews in twice (once as the table to be updated
and once as t1) or at least not without limiting which rows you want to
update.
I think you probably just want:
update f_test_pageviews set sub_key=t2.id from d_user t2 where
f_test_pageviews.subscriber_key=t2.user_id;
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