Hi,
Joins are fine to use, the problem here is you have them in the wrong order.
SELECT p.prod_id, p.prod_name, p.prod_no, chp.cat_id,
c.cat_name, c.cat_parent, pr.price
FROM products as p
LEFT JOIN categories_has_products as chp ON chp.prod_id = p.prod_id
LEFT JOIN categories as c ON chp.cat_id = c.cat_id
LEFT JOIN prices as pr ON pr.prod_id = p.prod_id
WHERE prod_featured = '1'
ORDER BY RAND(), pr.price ASC
LIMIT 6
This is doing:
join products to categories_has_products (using prod_id) -- fine
then join categories_has_products to categories (using cat_id) -- fine
then join categories to prices (using prod_id) --- not fine
You could try
SELECT p.prod_id, p.prod_name, p.prod_no, chp.cat_id,
c.cat_name, c.cat_parent, pr.price
FROM products as p
LEFT JOIN prices as pr ON pr.prod_id = p.prod_id
LEFT JOIN categories_has_products as chp ON chp.prod_id = p.prod_id
LEFT JOIN categories as c ON chp.cat_id = c.cat_id
and it should work quickly because it does:
join products to prices (using prod_id)
then join prices to categories_has_products (using prod_id)
then join categories_has_products to categories (using cat_id)
Afan Pasalic wrote:
?!?!? Yup. It works! YEAH!!! :) :) :)
And pretty fast too!
Ok. I was suggested to use JOIN. But you DON'T use it?
-afan
On Thu, 2006-02-09 at 13:09 +1100, Chris wrote:
Oops, missed this one before I sent that other email.
I think it's the order of your joins playing up.
LEFT JOIN categories as c ON chp.cat_id = c.cat_id
LEFT JOIN prices as pr ON pr.prod_id = p.prod_id
That means it will join categories -> prices - not what you want.
Try this query:
SELECT p.prod_id, p.prod_name, p.prod_no, chp.cat_id,
c.cat_name, c.cat_parent, pr.price
FROM
products p,
categories_has_products chp,
categories c,
prices pr
WHERE
chp.prod_id = p.prod_id
AND chp.cat_id = c.cat_id
AND pr.prod_id = p.prod_id
AND prod_featured = '1'
ORDER BY RAND(), pr.price ASC
LIMIT 6
Afan Pasalic wrote:
The result display is bad (at least on at email). Here is a snapshot:
http://afan.net/bhw/snapshot1.png
-afan
On Wed, 2006-02-08 at 19:39 -0500, Afan Pasalic wrote:
Hm. Have no idea what does it means:
table
type
possible_keys
key
key_len
ref
rows
Extra
p
ALL
NULL
NULL
NULL
NULL
1268
Using
where;
Using
temporary; Using filesort
chp
index
NULL
PRIMARY
8
NULL
1741
Using
index
c
eq_ref
PRIMARY
PRIMARY
4
chp.cat_id
1
pr
ALL
NULL
NULL
NULL
NULL
10231
-afan
On Thu, 2006-02-09 at 09:53 +1100, Chris wrote:
Hi,
Grab that query and run it through mysql with 'explain', so:
explain SELECT p.prod_id, p.prod_name, p.prod_no, chp.cat_id,
c.cat_name, c.cat_parent, pr.price
FROM products as p
LEFT JOIN categories_has_products as chp ON chp.prod_id = p.prod_id
LEFT JOIN categories as c ON chp.cat_id = c.cat_id
LEFT JOIN prices as pr ON pr.prod_id = p.prod_id
WHERE prod_featured = '1'
ORDER BY RAND(), pr.price ASC
LIMIT 6
That will show you whether you are using the database indexes or not.
If you can't work it out then post the explain output.
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