Find a photo for each of 10 random Facebook friends in FQL?

I'm attempting to开发者_运维百科 do a Facebook FQL Multiquery (via JS SDK FB.api call) to load a single photo for each of 10 random Facebook friends where they have been tagged (aka "Show 10 random friends and a photo of theirs"). Here is my Javascript array of queries:

   var queries = {
            q1:"SELECT uid, name FROM user WHERE uid IN (Select uid2 from friend where uid1 = " + user_id 
                 + " order by rand() limit 10) ",
            q2: "SELECT pid, subject from photo_tag where subject in (SELECT uid from #q1) limit 10",
            q3:"SELECT src from photo where pid in (SELECT pid from #q2)"};

What I was trying to do:

1. Query 1: Get the userid and name of 10 random friends of the user.
2. Query 2: Get the photo id and subject name of phototags where the user ids matched those from query 1.
3. Query 3: Select the image src from the photos that matched those in query 2.

The problem is that I have no way in Query 2 to select DISTINCT records by users. That is, I cannot tell Facebook to return just a single photo for each user. Right now, it is arbitrary and all 10 rows could be different photo tags of the same user.

I could do some looping in Javascript and make a single FQL query for a pic for each matched user, but that just seems wrong. Any other suggestions on how to do this efficiently, preferably directly in FQL?

Thanks!

Well, I solved this awhile back and am closing this for completeness.

What I had to do was NOT do it all in a single multiquery. I had to FIRST make a single query to retrieve some random friends, THEN make a multiquery where we load a random photo for each of these friends.

FB.api(
        {
            method: 'fql.query',
            query: "SELECT uid, name FROM user WHERE uid IN (Select uid2 from friend where uid1 = " + user_id 
                 + " order by rand() limit 8) "
        }, function (response) {
            var queries = {};
            for (x in response) {
                if (typeof photoArray[response[x].uid] == 'undefined') photoArray[response[x].uid] = [];
                photoArray[response[x].uid]['name'] = response[x].name;
                queries[response[x].uid] = "SELECT src_big, caption from photo where pid in (SELECT pid from photo_tag where subject =" + response[x].uid + " order by rand() limit 1) ";
            }

            FB.api(
                {
            method: 'fql.multiquery',
            queries: queries
                },
                function(response) {


                    for (y in response) {
                        if (typeof response[y].fql_result_set[0] != 'undefined') {
                            photoArray[response[y].name]['image_src'] = response[y].fql_result_set[0].src_big;
                                        // Do what you want with the pics
                        }
                    }