public function getDefinition()
    {
        $columnNames = " (`" . implode("`,`", $this->columnNames) . "`)";
        switch ($this->indexType) {
            case self::PRIMARY:
                return "PRIMARY KEY" . $columnNames;
                break;
            case self::INDEX:
                return "KEY `" . $this->indexName . "`" . $columnNames;
                break;
            case self::UNIQUE:
                return "UNIQUE `" . $this->indexName . "`" . $columnNames;
                break;
            case self::FULLTEXT:
                return "FULLTEXT KEY `" . $this->indexName . "`" . $columnNames;
                break;
        }

        return "";
    }