I believe there is an error in this line in Codeigniter using Active Records, but I cant seem to figure out the syntax on the second line with IFNULL() and COUNT()
$this->db->select('places.*, category.*')
->select('IFNULL(COUNT("places_reviews.place_id"), 0) AS num_reviews')
->from('places')
->join('category', 'places.category_id = category.category_id')
->join('places_reviews', 'places_reviews.place_id = places.id', 'left')
->where('places.category_id', $category_id)
->group_by('places.id')
->limit($limit, $offset)
->order_by($sort_by, $sort_order);