ok, I did: SELECT count(DISTINCT c.cliente_id) as qtd_client,count(cm.cm_id) as qtd_computers
GREAT. It works.
Please, explain me why and how it works, I wanna learn and do by myself next time :)
2009/11/18 Oliveiros C,
<oliveiros.cristina@marktest.pt>Try substituting the SELECT count(c) as qtd_client,count(cm) as qtd_computers
by
SELECT count( DISTINCT c.cliente_id) as qtd_client,count(/* put here the primary key of the computer table */ ) as qtd_computers
Then tell me if it output what you want
Best,
Oliveiros
----- Original Message -----
Sent: Wednesday, November 18, 2009 4:55 PM
Subject: [SQL] need nelp with aggregate functions
The DB structure is in attachment.
I with the number of clients and the number of computers that have processors with "manufacturer" = "INTEL" and "speed" = "2GB"
I am trying:
select count(c) as qtd_client, count(cm) as qtd_computers
from cliente c
inner JOIN computer cm on (c.cliente_id = cm.cliente_id)
inner join processor p on (cm.processor_id = p.processor_id)
inner join speed s on (s.speed_id = p.speed_id)
INNER JOIN manufacturer m on (p.manufacturer_id=m.manufacturer_id)
where m.manufacturer = 'INTEL'
and s.speed = '2GB'
but is not working
anyone can help me?
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