This can be done in one query using subselects.
El Vie 05 Sep 2003 15:49, John W. Holmes escribió:
> Oz wrote:
> > I have a php page where I would like to list a numer of companies as
> > below:
> >
> > 1- retrieve all distinct company names from TableA (SELECT company_name
> > FROM TableA)
>
> CREATE TEMPORARY TABLE temp1 SELECT DISTINCT(company_name) FROM TableA
>
> > 2- retrieve all distinct company names from TableB
> > 3- combine the two lists as list1
>
> INSERT INTO temp1 SELECT DISTINCT(company_name) FROM TableB
>
> > 4- retrieve all distinct company names from TableC
>
> CREATE TEMPORARY TABLE temp2 SELECT DISTINCT(company_name) FROM TableC
>
> > 5- retrieve all distinct company names from TableD
> > 6- combine the two lists as list2
>
> INSERT INTO temp2 SELECT DISTINCT(company_name) FROM TableD
>
> > 7- display company names in list1 that don't exist in list2
>
> SELECT t1.company_name FROM temp1 t1 LEFT JOIN temp2 t2 ON
> t1.company_name = t2.company_name WHERE t2.company_name IS NULL
>
> > MySql version is 3.23.56 3.23.56 , so I cannot use UNION.
> >
> > I would like to accomplish this with as little php code as possible,
> > using mostly SQL.
>
> How about using all SQL? :)
>
> All of this is in the MySQL manual, btw...
>
> --
> ---John Holmes...
>
> Amazon Wishlist: www.amazon.com/o/registry/3BEXC84AB3A5E/
>
> php|architect: The Magazine for PHP Professionals – www.phparch.com
--
Porqué usar una base de datos relacional cualquiera,
si podés usar PostgreSQL?
-----------------------------------------------------------------
Martín Marqués | mmarques@unl.edu.ar
Programador, Administrador, DBA | Centro de Telematica
Universidad Nacional
del Litoral
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