ขอสอบถามข้อมูลเกี่ยวกับเงื่อนไขการ create table โดยใช้ php

<?
include("connect.php");
$string=$_SESSION["UserID"] ;;
// sql to create table
$sql = "CREATE TABLE dummy$string (
    id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    firstname VARCHAR(30) NOT NULL,
    lastname VARCHAR(30) NOT NULL,
    email VARCHAR(50),
    reg_date TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
    )";
    
    if ($con->query($sql) === 1) {
      echo "Table MyGuests created successfully";
    } else {
      echo "Error creating table: " . $con->error;
    }
    
    $con->close();
    ?>