code: private String redisColumnKey(SqlpKit.FLAG flag) {
  		StringBuilder key = new StringBuilder(this._getUsefulClass().toGenericString());
  		String[] attrs = this._getAttrNames();
  		Object val;
  		for (String attr : attrs) {
  			val = this.get(attr);
  			if (null == val) {
  				continue;
  			}
  			key.append(val.toString());
  		}
  		key = new StringBuilder(HashKit.md5(key.toString()));
  		if (flag.equals(SqlpKit.FLAG.ONE)) {
  			return "data:"+key;
  		}
  		return "datas:"+key;
  	}
docs: redis key for attrs' values
  @param flag : ids or id store
  @return data[s]:md5(concat(columns' value))