public function addWhere($field, $value, $sign = '=', $whereConcat = 'AND')
    {
        $fieldWhere = (0 < count($this->wheres) ? ' ' . $whereConcat . ' ' . $field : $field);
        $fieldBind  = ':' . strtolower($field);

        if (isset($this->binds[$fieldBind])) {
            $counter = 0;
            while ($counter < 20) {

                if (isset($this->binds[$fieldBind . '__' . $counter++])) {
                    continue;
                }

                $fieldBind .= '__' . $counter;
                break;
            };
        }

        $this->wheres[]          = $fieldWhere . ' ' . $sign . ' ' . $fieldBind;
        $this->binds[$fieldBind] = $value;

        return $this;
    }