/// <summary> /// 查询数据库聚合值。 /// </summary> /// <param name="commandText">SQL字符串。</param> /// <param name="parameters">参数实例对象。</param> /// <param name="commandType">命令类型。</param> /// <returns>返回聚合值实例对象。</returns> public object ExecuteScalar(string commandText, object parameters = null, CommandType commandType = CommandType.Text) => _executor.ExecuteScalar(commandText, parameters, commandType);