Take query true when one clause is false - sql

Question

This is my query
SELECT pl.NAME
,pl.id_product
,pl.link_rewrite
,i.id_image
,ar.id_auctions_rutcom
,ar.actual_bid_price
,ar.start_price
,ar.min_price
,ar.buy_now_price
,ar.finish_date
FROM ps_image i
,ps_auctions_rutcom ar
,ps_product_lang pl
WHERE ar.finish_date > '2013-07-26 11:18:15'
AND ar.start_date < '2013-07-26 11:18:15'
AND ar.active = 1
AND ar.finish = 0
AND pl.id_product = ar.id_product
AND i.id_product = ar.id_product
AND i.cover = 1
AND pl.id_lang = 6
I have problem when on table ps_image is no image where i.id_product = ar.id_product my query return false. How to change query to set true?

Answer 1

You should learn about JOIN. Google it.
Your query is equivalent to INNER JOIN:
SELECT
pl.name, pl.id_product, pl.link_rewrite, i.id_image, ar.id_auctions_rutcom,
ar.actual_bid_price, ar.start_price, ar.min_price, ar.buy_now_price, ar.finish_date
FROM ps_auctions_rutcom ar
INNER JOIN ps_product_lang pl
ON pl.id_product = ar.id_product
AND pl.id_lang = 6
INNER JOIN ps_image i
ON i.id_product = ar.id_product
AND i.cover = 1
WHERE ar.finish_date > '2013-07-26 11:18:15'
AND ar.start_date < '2013-07-26 11:18:15'
AND ar.active = 1
AND ar.finish = 0
With an INNER JOIN, if there is no matching row in the related table, the row is omitted from the result set.
Now, you should use an OUTER JOIN, in which case the row is still in the result set and the missing information is set to NULL.
SELECT
pl.name, pl.id_product, pl.link_rewrite, i.id_image, ar.id_auctions_rutcom,
ar.actual_bid_price, ar.start_price, ar.min_price, ar.buy_now_price, ar.finish_date
FROM ps_auctions_rutcom ar
INNER JOIN ps_product_lang pl
ON pl.id_product = ar.id_product
AND pl.id_lang = 6
LEFT OUTER JOIN ps_image i
ON i.id_product = ar.id_product
AND i.cover = 1
WHERE ar.finish_date > '2013-07-26 11:18:15'
AND ar.start_date < '2013-07-26 11:18:15'
AND ar.active = 1
AND ar.finish = 0

Answer 2

You can add in your query to make sure ps_image has not null
Where i.id_product IS NOT NULL

Answer 3

You should separate your joins from your filters, then use a left join to provide all the results
regardless of whether an image exists
FROM ps_auctions_rutcom ar
left join
ps_image i on i.id_product = ar.id_product
and i.cover = 1
left join
ps_product_lang pl on pl.id_product = ar.id_product
and pl.id_lang = 6
WHERE ....