Question

select 
      picks.`fbid`, 
      picks.`time`, 
      categories.`name` as cname, 
      options.`name` as oname, 
      users.`name` 
   from 
      picks 
         left join categories 
            on (categories.`id` = picks.`cid`) 
         left join options 
            on (options.`id` = picks.oid) 
         left join users 
            on (users.fbid = picks.`fbid`) 
   order by 
      time desc

that query returns a result that like:

my question is…. I would like to modify the query to select only DISTINCT fbid’s. (perhaps the first row only sorted by time)

can someone help with this?

Answer 1

select
      p2.fbid,
      p2.time,
      c.`name` as cname, 
      o.`name` as oname, 
      u.`name` 
   from
      ( select p1.fbid, 
               min( p1.time ) FirstTimePerID
           from picks p1
           group by p1.fbid ) as FirstPerID

         JOIN Picks p2
            on FirstPerID.fbid = p2.fbid
           AND FirstPerID.FirstTimePerID = p2.time

            LEFT JOIN Categories c
               on p2.cid = c.id

            LEFT JOIN Options o
               on p2.oid = o.id

            LEFT JOIN Users u
               on p2.fbid = u.fbid
   order by 
      time desc

I don’t know why you originally had LEFT JOINs, as it appears that all picks must be associated with a valid category, option and user… I would then remove the left, and change them to INNER joins instead.

The first inner query grabs for each fbid, the FIRST entry time which will result in a single entity for the FBID. From that, it re-joins to the picks table for the same ID and timeslot… then continues for the rest of the category, options, users join criteria of that single entry.