protected function _generateSafeAlterTableColumnOperation($table, $columns, $functionName)
	{
		$query = "ALTER TABLE $table ";

		foreach ($columns as $columnData)
		{
			$query .= $this->$functionName($table, $columnData) . ',';
		}

		$query = rtrim($query, ',') . ';';

		return $query;
	}