Re: [SQL] Join Advice and Assistance
Rob, Thanks for the reply... > If you want records for user without email addresses you will need an outer > join on user_emailaddrs > > /* untested */ > select u.userId, u.lname, u.lastname ,m.startdate, a.emailaddr > from users u > join usermetas m on u.userid = m.userid > left join user_emailaddrs a on m.userid = a.userid My question was related more toward eliminating the query returning a record for each record in the one-to-many table. I see now that I'm going to have to aggregate the e-mail addresses in order to return a single row. Thanks again. -- Gary Chambers /* Nothing fancy and nothing Microsoft! */ -- Sent via pgsql-sql mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
Re: [SQL] Join Advice and Assistance
My mistake. Should answer these things late at night. I think you will find that arrays will be your friend[s] On 02/22/2010 08:51 AM, Gary Chambers wrote: Rob, Thanks for the reply... If you want records for user without email addresses you will need an outer join on user_emailaddrs /* untested */ select u.userId, u.lname, u.lastname ,m.startdate, a.emailaddr from users u join usermetas m on u.userid = m.userid left join user_emailaddrs a on m.userid = a.userid My question was related more toward eliminating the query returning a record for each record in the one-to-many table. I see now that I'm going to have to aggregate the e-mail addresses in order to return a single row. Thanks again. -- Gary Chambers /* Nothing fancy and nothing Microsoft! */ -- Sent via pgsql-sql mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
Re: [SQL] Join Advice and Assistance
To expand on Rob's reply:
If you want to return a single row for each user, regardless of the number
of email addresses, you might use ARRAY() with a subquery, eg (haven't
tested this to make sure it completely works):
SELECT u.*, um.*, ARRAY(SELECT emailaddr FROM user_emailaddrs em WHERE
em.userid = u.userid AND em.is_active) AS email_addresses
FROM users u INNER JOIN usermetas um ON u.userid = um.userid;
Of course, this will return the addresses as a character varying[], with
output like {[email protected],[email protected]}, and would require some minor
contortions to present it to users cleanly. The array_to_string function may
help you make it easier to display the results.
http://www.postgresql.org/docs/8.4/static/functions-array.html#ARRAY-FUNCTIONS-TABLE
Hope this helps,
--Stephen Belcher
On Mon, Feb 22, 2010 at 12:05 PM, Rob Sargent wrote:
> My mistake. Should answer these things late at night.
>
> I think you will find that arrays will be your friend[s]
>
>
> On 02/22/2010 08:51 AM, Gary Chambers wrote:
>
>> Rob,
>>
>> Thanks for the reply...
>>
>> If you want records for user without email addresses you will need an
>>> outer
>>> join on user_emailaddrs
>>>
>>> /* untested */
>>> select u.userId, u.lname, u.lastname ,m.startdate, a.emailaddr
>>> from users u
>>> join usermetas m on u.userid = m.userid
>>> left join user_emailaddrs a on m.userid = a.userid
>>>
>>
>> My question was related more toward eliminating the query returning a
>> record for each record in the one-to-many table. I see now that I'm
>> going to have to aggregate the e-mail addresses in order to return a
>> single row. Thanks again.
>>
>> -- Gary Chambers
>>
>> /* Nothing fancy and nothing Microsoft! */
>>
>
> --
> Sent via pgsql-sql mailing list ([email protected])
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-sql
>
Re: [SQL] Join Advice and Assistance
Stephen,
> If you want to return a single row for each user, regardless of the number
> of email addresses, you might use ARRAY() with a subquery, eg (haven't
> tested this to make sure it completely works):
Your query worked perfectly!
> Of course, this will return the addresses as a character varying[], with
> output like {[email protected],[email protected]}, and would require some minor
> contortions to present it to users cleanly. The array_to_string function may
> help you make it easier to display the results.
Absolutely -- and thank you for the suggestion. I'll be retrieving
the results of the query through PHP, so cleanup in the query may even
be a performance degradation.
> Hope this helps,
You and Rob Sargent have helped a great deal. Thanks to both of you.
-- Gary Chambers
/* Nothing fancy and nothing Microsoft! */
--
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