private function getWhereInString()
    {
        // String holder
        $string = '';

        // If there are not where in conditions, return empty
        if (!count($this->whereIn)) {
            return $string;
        }

        // Iterate where creating the full conditions
        foreach ($this->whereIn as $where) {
            $string .= ' AND ' . $where['column'] . ' IN (' . implode(', ', $where['values']) . ')';
        }

        // Return complete where in string
        return $string;
    }