how to get last insert id after insert query in codeigniter active record

#how to get last insert id after insert query in codeigniter active record Example: For add data into table, function add_post($post_data){    $this->db->insert(‘posts’, $post_data);    $insert_id = $this->db->insert_id();    return  $insert_id; } Here, $insert_id = $this->db->insert_id(); returns the last inserted Id.