i'm having 2 tables: members and comments. I select all members, and then join comments. But in comments I'm selecting some SUM of points, and if user never commented, I can't get that user in listing?!

So how to select default value for SUM, or some other solution:

SELECT c.comment_id AS item_id, m.member_id AS member_id, m.avatar, 
            SUM(c.vote_value) AS vote_value, SUM(c.best) AS best, 
            SUM(c.vote_value) + SUM(c.najbolji)*10 AS total
            FROM members m
            LEFT JOIN comments c ON m.member_id = c.author_id
            GROUP BY c.author_id
            ORDER BY m.member_id DESC
            LIMIT {$sql_start}, {$sql_pokazi}