Koen Bok escreveu:
I am doing some optimization on our search, but I need some advise...
table: item
id name
--------------------------------------
1 iPod
2 Zune
3 Walkman
table: search_item
id_search id_item
--------------------------------------
1 1
1 2
1 3
2 2
2 3
3 1
3 3
Now what I want to have is the items that match with id_search 1 and 2
and 3. Therefore I use the following SQL query.
SELECT * FROM item WHERE id IN
(SELECT id_item FROM search_item WHERE id_search=1 AND id_item IN
(SELECT id_item FROM search_item WHERE id_search=2 AND id_item IN
(SELECT id_item FROM search_item WHERE id_search=3)));
This should only return id_item 3. Would this be the best SQL query to
get this result? I have the feeling there should be something better,
but I cannot find it. Anyone has a hint?
SELECT * FROM item WHERE id IN
(SELECT id_item FROM search_item WHERE id_search=1
INTERSECT
SELECT id_item FROM search_item WHERE id_search=2
INTERSECT
SELECT id_item FROM search_item WHERE id_search=3);
Osvaldo
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