private function getJoinString()
    {
        // If there are not joins, return empty
        if (!count($this->orderBy)) {
            return '';
        }

        // Create join strings
        $joins = array_map(function ($join) {
            return $join['type'] . ' JOIN ' . $join['table'] . ' ON ' . $this->table . '.' . $join['first'] . $join['operator'] . $join['table'] . '.' . $join['second'];
        }, $this->joins);

        // Return complete join string
        return implode(' ', $joins);
    }