Question

I need to get a list of Articles sorted by the latest Comment from a related table joined on article.id = message.article_id using Kohana ORM. I managed to build a query that GROUPS and only then ORDERS:

SELECT * 
FROM  `articles` 
LEFT JOIN  `comments` ON (  `articles`.`id` =  `comments`.`article_id` ) 
GROUP BY  `comments`.`item_id` 
ORDER BY  `datetime` DESC 

The query I am trying to build is:

SELECT * FROM `articles` LEFT JOIN 
(SELECT article_id, MAX(datetime) as datetime FROM comments GROUP BY (article_id)) 
AS b ON `articles`.`id` = b.`article_id` 
ORDER BY datetime 

I have no idea how to rewrite it into Kohana ORM… (and I can’t avoid ORM because there is a ton of code that depends on it)

Answer 1

$subquery = DB::select('article_id', array('MAX("datetime")','datetime'))
    ->from('comments')
    ->group_by('article_id');

$s = ORM::factory('article')
    ->join(array($subquery, 'b'), 'LEFT')
    ->on('article.id','=','b.article_id')
    ->order_by('datetime')
    ->find_all();

This is the translation of your query, I’m not really sure if it will work