Create a table with WordPress custom plugin

<?php

function my_first_plugin_code(){
 
 /* create table */
 
global $wpdb;
$charset_collate = $wpdb->get_charset_collate();

$table_name = $wpdb->prefix . "myplugintable";

$sql = "CREATE TABLE $table_name (
  id mediumint(9) NOT NULL AUTO_INCREMENT,
  time datetime DEFAULT '0000-00-00 00:00:00' NOT NULL,
  name tinytext NOT NULL,
  text text NOT NULL,
  url varchar(55) DEFAULT '' NOT NULL,
  PRIMARY KEY  (id)
) $charset_collate;";

require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
dbDelta( $sql );