A simple WordPress plugin the creates custom table on plugin activation. Visit https://www.davidangulo.xyz/ for more information.

databasetable.php

<?php
/*
Plugin Name: Create database table
Plugin URI: https://www.davidangulo.xyz/portfolio/
Description: A simple WordPress plugin that creates a database table on activation.
Version: 1.0.0
Author: David Angulo
Author URI: https://www.davidangulo.xyz/
License: GPL2
*/

register_activation_hook( __FILE__,"myPluginCreateTable");
function myPluginCreateTable() {
	global $wpdb;
	$charset_collate = $wpdb->get_charset_collate();
	$table_name = $wpdb->prefix . "customtable";
	$sql = "CREATE TABLE `$table_name` (
	`id` int(11) NOT NULL,
	`column2` varchar(220) DEFAULT NULL,
	`column3` varchar(220) DEFAULT NULL,
	`column4` int(11) DEFAULT '1',
	PRIMARY KEY(id)
	) ENGINE=MyISAM DEFAULT CHARSET=latin1;
	";
	if($wpdb->get_var("SHOW TABLES LIKE '$table_name'") != $table_name) {
		require_once(ABSPATH . "wp-admin/includes/upgrade.php");
		dbDelta($sql);
	}
}

//Visit the tutorial for more information
//https://www.davidangulo.xyz/website-development/how-to-create-database-tables-when-your-plugin-is-activated/