Question

I have 2 tables: players and items. Now I’m looking for player who has item with known properties ex.

SELECT players.`name` FROM `players`
INNER JOIN `items` ON players.`id`=items.`ownerId` 
WHERE items.`itemType` = 1 AND items.`itemClass` = 2 AND items.`itemColor` = 3

How i can find player which has more than one item i want? It is even possible in one query?

Ex. i wanna find player which has both items : type=1 class=2 color=3 , type=2 class=3 color=4

I have an idea how to do it in multiple querys: just add players.id IN (…) on every next query.

Thanks for all your help!

Answer 1

The best way to do this is with aggregation.

select i.ownerId
from Items i
group by i.ownerId
having max(case when i.itemType = 1 and i.itemClass = 2 and i.itemColor = 3
                then 1 else 0
           end) = 1 and
       max(case when i.itemType = 2 and i.itemClass = 3 and i.itemColor = 4
                then 1 else 0
           end) = 1

If you want other information about the owner, you need to join in the players table.

In MySQL, you can simplify the having clause to:

having max(i.itemType = 1 and i.itemClass = 2 and i.itemColor = 3) = 1 and
       max(i.itemType = 2 and i.itemClass = 3 and i.itemColor = 4) = 1