I want to make it using codeigniter query_builder function. Not getting Idea, please help.
$this->db->query("SELECT city as popularcity FROM(SELECT city,count(city) as
countcity FROM ads LIMIT 0, 6) as t ORDER BY MAX(countcity)");
$this->db->query("SELECT city as popularcity, countcity
FROM
(SELECT city, count(city) as countcity FROM ads GROUP BY city) as t
ORDER BY countcity DESC LIMIT 0, 6");
Try below code,
$this->db->select("city as popularcity, countcity");
$this->db->from("(SELECT city, count(city) as countcity FROM ads GROUP BY city) as t");
$this->db->order_by("countcity DESC");
$this->db->limit(0,6);