สอบถาม วิธีเพิ่มข้อมูล PHP และ MySQLi ด้วยคำสั่ง prepare + SQL

    $conn = new mysqli("127.0.0.1", "root", "", "db_coffee");
    $conn->query("set names utf8");
    $pvc_title = $conn->real_escape_string("ทดสอบ");
    $sql = " insert into tb_province values ( NULL, ? ) ";
    $pp = $conn->prepare($sql);
    $pp->bind_param("s", $pvc_title);
    $pp->execute();
    if( $pp->affected_rows ) {
        echo "insert id = ".$pp->insert_id;
    } else {
        echo "insert failed";
    }