Create custom database table on WordPress plugin activation

gistfile1.php

register_activation_hook( __FILE__, 'endo_create_custom_table' );

function endo_create_custom_table() {

	global $wpdb;

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

	$sql = "CREATE TABLE $table_name(
		id mediumint(9) NOT NULL AUTO_INCREMENT,
		entry_id VARCHAR(50) NOT NULL,
		date datetime,
		email VARCHAR(50) CHARACTER SET utf8,
		param1 VARCHAR(50) CHARACTER SET utf8,
		param2 mediumint(1) DEFAULT 0,
		UNIQUE KEY id(id)
		) COLLATE utf8_general_ci;";

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

}