$arrRecommendData = $objQuery->select("recommend_product_id, comment", "dtb_recommend_products", "product_id = ?", array($product_id));

 ↓

$from = "dtb_recommend_products AS rp JOIN dtb_products AS p ON rp.recommend_product_id = p.product_id";
$where = "rp.product_id = ? AND p.status = 1 AND p.del_flg = 0";
$arrRecommendData = $objQuery->select("rp.recommend_product_id, rp.comment", $from, $where, array($product_id));