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From: Dimitri Fontaine <dfontaine@hi-media.com>
To: Guy Deleeuw <G.De_Leeuw@eurofer.be>
Cc: pgsql-admin@postgresql.org
Subject: Re: How to use an alias name in the current select
Date: Wed, 24 Mar 2010 20:09:18 +0100
Message-ID: <m2d3ytwn8h.fsf@hi-media.com> (raw)
In-Reply-To: <4BAA40E2.3000805@eurofer.be>
References: <4BAA40E2.3000805@eurofer.be>

Hi,

Guy Deleeuw <G.De_Leeuw@eurofer.be> writes:
>    SELECT
>          t_orders_articles.k_id            AS k_id
>         ,t_orders_articles.quantity        AS order_qty
>         ,(SELECT sum(quantity) FROM t_deliveries_articles WHERE article_id =
> t_orders_articles.k_id) AS delivery_qty
>         , (t_orders_articles.quantity - delivery_qty)       AS qty
>       FROM t_orders_articles
>        ......;
>
> How can I make that without having 2 select call ?

Put it as a relation in a subquery, or use WITH if using 8.4.

SELECT k_id, order_qty, quantity, delivery_qty,
  quantity - delivery_qty as qty
 FROM (
    SELECT
          t_orders_articles.k_id            AS k_id
         ,t_orders_articles.quantity        AS order_qty
         ,(SELECT sum(quantity) FROM t_deliveries_articles WHERE article_id =
 t_orders_articles.k_id) AS delivery_qty
         , t_orders_articles.quantity 
       FROM t_orders_articles
      ) as t;


Or

WITH t AS (
    SELECT
          t_orders_articles.k_id            AS k_id
         ,t_orders_articles.quantity        AS order_qty
         ,(SELECT sum(quantity) FROM t_deliveries_articles WHERE article_id =
 t_orders_articles.k_id) AS delivery_qty
         , t_orders_articles.quantity 
       FROM t_orders_articles
)
SELECT k_id, order_qty, quantity, delivery_qty,
  quantity - delivery_qty as qty
  FROM t;

Regards,
-- 
dim

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  Subject: Re: How to use an alias name in the current select
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