Question

i have a online application for wich i require a sort of dashboard (to use the white-space).

There are three tables used for the operation:

1.) categories: id, name
2.) entries: id, name, description, category_id, created, modified
3.) entryimages: id, filename, description, entry_id

on the dashboard i want to show 4-5 entries (with thumbnail images, so i require joins to the entryimages table and the categories table) for each category.

I read through some articles (and threads on s.o.) like this one:
http://www.xaprb.com/blog/2006/12/07/how-to-select-the-firstleastmax-row-per-group-in-sql/

But am still not getting it right, i’ve tried to first extract all categories and for each and every category build a query and with “all union” attach them to one, but that is not working.
The last version of code i used:

foreach($categories as $id => $name)
{
    $query .= "SELECT   `entry`.`id`,
            `entry`.`name`,
            `entry`.`description`,
            `entry`.`category_id`,
            `entry`.`created`,
            `entry`.`modified`,
            `entryimages`.`filename`,
            `entryimages`.`description`
            FROM `entries` as `entry` LEFT JOIN `entryimages` ON `entryimages`.`entry_id` = `entry`.`id`
WHERE `entry`.`category_id` = $id ";

            if($i < count($groups))
            {
                $query .= 'UNION ALL ';
            }

            $i++;
        }

        $result = mysql_query($query);

Does anybody know what is the best right to accomplish this operation?

Thanks 1000

Answer 1

On the dashboard if you want to show three entries, the way you are doing is wrong. If my understanding is right, the entire query will be something like

"SELECT `entry`.`id`,
        `entry`.`name`,
        `entry`.`description`,
        `entry`.`category_id`,
        `entry`.`created`,
        `entry`.`modified`,
        `entryimages`.`filename`,
        `entryimages`.`description`
    FROM `entries` as `entry` 
    INNER JOIN categories 
        ON (entry.category_id = categories.id)
    LEFT JOIN (SELECT * FROM `entryimages` WHERE `entry_id` = `entry`.`id` LIMIT 1) AS `entryimages`
        ON `entryimages`.`entry_id` =`entry`.`id`    
    ORDER BY `entry`.`created` DESC LIMIT 5";