code: public M fetchOne(String... columns) {
  		if (null == columns) {
  			return this.fetchOne();
  		}
  		//from db
  		if (!this.syncToRedis) {
  			return this.findFirst(SqlpKit.selectOne(this, columns));
  		}
  		//from redis
  		return this.fetchOneFromRedis(columns);
  	}
docs: <b>Advanced Function</b>.
  you can fetch FirstOne Model:just contains columns, use any column value can do this.the data from DB.