Question

I have this huge ugly query below, i’d like to sort by it in a catalog view. Thinking something like http://wow.dev:3000/catalog_items?&order=deals. A million thank yous in advance for any comments or answers.

select 100 - round((current_price / item.estimated_price)*100) as percent, item.cached_thumbnail_url, item.item_id, it.name,
          ci.current_price, ci.close_date
           from item
           join catalog_item ci on ci.item_id = item.item_id
           join item_translations as it on (it.item_id = item.item_id)
           where  (100 - round((current_price / item.estimated_price)*100)) > 49 and 
           item.estimated_price > 0 and ci.current_price > 0 and ci.close_date > now() and item.active = 1 and ci.active = 1 and 
           (current_price / estimated_price) < 1
           order by (ci.close_date < DATE_ADD(now(), INTERVAL 17 hour))  and (item.estimated_price - current_price) desc
           limit 12

Answer 1

Not sure how this could be related to ROR, but anyways:

1. You have 100 - round((current_price / item.estimated_price)*100) as percent in your SELECT clause, yet anyway using the same expression in WHERE conditions.

2. Can item.estimated_price be less than zero? If not the item.estimated_price > 0 condition is excessive, if it’s zero the (100 - round((current_price / item.estimated_price)*100)) > 49 condition will be false

3. The (current_price / estimated_price) < 1 is excessive for same reasons

So you query can be rewritten a bit more clearly like this:

select (100 - round((current_price / item.estimated_price)*100)) as percent,
   item.cached_thumbnail_url, item.item_id, it.name,
   ci.current_price, ci.close_date
from item
   join catalog_item ci on ci.item_id = item.item_id
   join item_translations as it on (it.item_id = item.item_id)
where
   percent > 49
   and ci.current_price > 0
   and ci.close_date > now()
   and item.active = 1
   and ci.active = 1
order by
   (ci.close_date < DATE_ADD(now(), INTERVAL 17 hour))
   and (item.estimated_price - current_price) desc
limit 12

This doesn’t improve the situation a lot, but I can’t say more without knowing any more reasons about your DB architecture.

BTW the link in your question doesn’t work (it’s you local link obviously)