Add new column to plugin table in new version

add_new_column_to_plugin_table_in_new_version.php

<?php

final class Plugin_Name {

	private function __construct() {
		register_activation_hook( __FILE__, array( $this, 'plugin_activation' ) );
  	}

	public function plugin_activation() {
		if ( get_option( 'plugin_version' ) != PLUGIN_VERSION ) {
			update_option( 'plugin_version', PLUGIN_VERSION );
		}

		$this->create_tables();
		$this->upgrade_tables();
	}

	public function create_tables() {
		// 	codes here...
	}
	
	public function upgrade_tables() {
		if ( get_option( 'plugin_version' ) == '1.2.0' ) {
			global $wpdb, $table_prefix;
			$plugin_tbl_name = $table_prefix . 'plugin_tbl_name';
			$the_upgrade_query = "ALTER TABLE `{$plugin_tbl_name}` ADD `products` TEXT NULL DEFAULT NULL AFTER `users`;";

			$wpdb->query( $the_upgrade_query );
		}
	}


}