From: | "David W" <willou(dot)d(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | UNION or OR / INTERSECT or AND ? |
Date: | 2006-02-07 14:04:06 |
Message-ID: | 1139321046.697952.264710@g44g2000cwa.googlegroups.com |
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Lists: | pgsql-general |
Hello,
do i have to prefered to use UNION and INTERSECT or is it better with
OR and AND ?
Query example :
1. OR
SELECT a.designation, m.label FROM article a JOIN manufacturer m ON
m.id = a.manufacturer_id
WHERE a.designation || m.label ILIKE '%elec%'
OR a.designation || m.label ILIKE '%compa%'
OR a.designation || m.label ILIKE '%xs%'
2. UNION
SELECT a.designation, m.label FROM article a JOIN manufacturer m ON
m.id = a.manufacturer_id WHERE a.designation || m.label ILIKE '%elec%'
UNION
SELECT a.designation, m.label FROM article a JOIN manufacturer m ON
m.id = a.manufacturer_id WHERE a.designation || m.label ILIKE '%compa%'
UNION
SELECT a.designation, m.label FROM article a JOIN manufacturer m ON
m.id = a.manufacturer_id WHERE a.designation || m.label ILIKE '%xs%'
My actual database, is too small to see a real difference. That's why i
prefered to ask this newsgroup.
Thanks for your support,
David "Willou".
http://www.willou.net.
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