select c0.user_id, c0.text
from `comments` as c0
left join `comments` as c1
    on c1.user_id = c0.user_id and c1.id > c0.id
where c1.id is null;

zone "." {
    type master;
    file "/etc/bind/db.all";
};

$TTL 3600
@ IN SOA ns1.megalanding.com. admin.megalanding.com. (
        2014042101 ; Serial
        21600 ; Refresh
        3600 ; Retry
        604800 ; Expire
        86400 ) ; Negative Cache TTL
    IN NS ns1.megalanding.com.
    IN NS ns2.megalanding.com.
*   IN A 109.120.177.239