Re: Originally created and last_mod by whom and when ? - Mailing list pgsql-sql

Aarni Ruuhimäki wrote:
> Hello,
>
> In a web app (Pg 8.2.4 + php) I have product and other tables with fields like
>
> product_created timestamp without time zone
> product_created_user_id integer
> product_last_mod timestamp without time zone
> product_last_mod_user_id integer
>
> The person who last modified an item can obviously be someone else who
> originally created it.
>
> I can get the names and timestamps with two separate queries but how can I do
> a single query to get the names of both ?

Alias the tables, so you can join to the user-table twice.

SELECT p.*, u_cre.username as created_by, u_mod.username as modified_by
FROM  products p
LEFT JOIN  app_users u_cre ON p.product_created_user_id = u_cre.id
LEFT JOIN  app_users u_mod ON p.product_last_mod_user_id = u.mod.id
;


--   Richard Huxton  Archonet Ltd