Message-ID: <44CA9E18.8020306@myemma.com>
Date: Fri, 28 Jul 2006 18:30:32 -0500
From: Erik Jones <erik@myemma.com>
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To: Fabian Peters <lists.fabian@e-lumo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: UPDATE with WHERE clause on joined table
References: <B45EBA38-2DFC-45E7-921B-16D52A986E7A@e-lumo.com>
In-Reply-To: <B45EBA38-2DFC-45E7-921B-16D52A986E7A@e-lumo.com>
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Fabian Peters wrote:
> Hi,
>
> I'm only very rarely using SQL, so please forgive me if I show any 
> obvious signs of ignorance...
>
> I've got three tables "customer", "address" and "country". I want to 
> set the "language" attribute on "customer" on rows returned by a 
> SELECT such as this:
>
> SELECT title, first_names, last_name, email, language, 
> country.country_name FROM ((customer JOIN address ON customer.eoid = 
> address.eoid_customer) JOIN country ON address.eoid_country = 
> country.eoid) WHERE email LIKE '%.es' AND country.country_name = 'SPAIN';
>
> That is, I want to set the "language" to 'Spanish' where the 
> "customer.email" is like '%.es' and where "country.country_name" is 
> 'SPAIN'.
>
> I've tried all sorts of places to put the JOIN and the WHERE clauses 
> within the UPDATE statement, but I just don't get it.
>
> I'd be most grateful for any help...
>
> TIA
>
> Fabian
>
> P.S.: One of my sorry attempts looked like this - which updates all 
> rows in "customer" so I figure the WHERE clause is not where it should 
> be:
>
> UPDATE customer SET language = 'Spanish' FROM ((customer AS 
> customer_address JOIN address ON customer_address.eoid = 
> address.eoid_customer) JOIN country ON address.eoid_country = 
> country.eoid) WHERE customer.email LIKE '%.es' AND 
> country.country_name = 'SPAIN'); 
The FROM clause is where you put relations other than the one you  are 
updating.  Try this:

UPDATE customer
SET language='Spanish'
FROM address ad, country co
WHERE customer.eoid=ad.eoid_customer AND ad.eoid_country=co.eoid
    AND co.country_name='SPAIN' AND customer.email LIKE '%.es';

Note that for demonstration purposes I've aliased the join tables and 
that (unfortunately) you can't alias the update table.

erik jones <erik@myemma.com>
software development
emma(r)