NYCPHP Meetup

[Peter Sawczynec]

SELECT at1.attribute_value 
FROM User_Attributes AS at1 
WHERE at1.attribute_name = 'email' 
AND at1.user_id IN 
(SELECT user_id FROM User_Attributes AS at2 WHERE at2.attribute_name =
'active' and at2.attribute_value = 'yes')

Above query does the right work, but can you exapand it to get me users's
firt_name from User_Attributes table too.

I need active user's name and email.

Gracias,
Pedro



-----Original Message-----
From: talk-bounces at lists.nyphp.org [mailto:talk-bounces at lists.nyphp.org] On
Behalf Of Carlos A Hoyos
Sent: Wednesday, March 01, 2006 11:06 PM
To: NYPHP Talk
Subject: Re: [nycphp-talk] A SQL Query Conundrum. I Need Your Assistance...



Two very simple options:
1- You can join with the same table multiple times just by giving it
different alias. So for example this following query will get all users id,

SELECT user.user_id, at1.attribute_value as name, at2.attribute_value as
email, FROM users AS user, User_Attributes AS at1,  User_Attributes AS at2
WHERE user.user_id = at1.user_id AND user.user_id = at2.user_id AND
at1.attribute_name = 'last_name' AND at2.attribute_name = 'email'

you get the idea...

2- You can use subqueries, for example to get emails for all active users:
select at1.attribute_value from User_Attributes AS at1 where
at1.attribute_name = 'email' and at1.user_id in
      select (user_id from User_Attributes AS at2 where  at2.attribute_name
= 'active' and at2.attribute_value = 'yes')

you get the point...

I know it's none of my business, but maybe you should use a query like that
one to de-normalize the table, I can't think of a good reason for such level
of normalization.



Carlos Hoyos, Tools Architect
Global Production Services - Tools, ibm.com
1133 Westchester Ave, # 2e 524, White Plains, NY 10604
Phone: 914.642.3569 TieLine: 224.3569
cahoyos at us.ibm.com

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