public function unique($column, $value, $table)
    {
        $db = new DB();
        $result = $db->db()->count(['db_name'=>__config()->database->db_name, 'table'=>$table, 'wheres' => [$column.' ='."'{$value}'"]]);
        $db->db()->close();
        if ($result === 0) {
            return true;
        } else {
            return false;
        }
    }