Question

I have a table ITEMS, which has the props id, site_id, frequency

So far i can list the items and order them by frequency from an array of id, using

SELECT * 
FROM items 
WHERE id IN(1549, 1550, 1635, 1637) 
ORDER BY site_id, frequency DESC

But i’d like to group my results by site_id with only one item that has the best (highest) frequency..

how do i do ?

Edit : I’d like to have the items that have the best frequency grouped by site_id (one result by site_id)

Answer 1

select i.*
from (
    select site_id, max(frequency) as MaxFrequency
    from item
    where id in (1549, 1550, 1635, 1637)    
    group by site_id
) im
inner join items i on im.site_id = i.site_id and im.MaxFrequency = i.frequency
where i.id in (1549, 1550, 1635, 1637)    

Note: This will give you more than one row per site_id if both have the same frequency.