What are two requirements when using Packet Flow Acceleration? （）(Choose two.)

A

Traffic needs be compressed.

B

Quality of service must be enabled.

C

A service tunnel must exist in at least one direction.

D

PFA must be enabled on the client-side WX device.

Which object may be used during query optimization to improve the performance for a subset of SELECT queries?（）

A、MQT

B、Trigger

C、Read Only Cursor

D、Stored Procedure

以昆虫为媒介而传播的疾病是（）

A、麻疹

B、戊型肝炎

C、艾滋病

D、流行性出血热

E、结核病

A UDT is a data type which:（）

A、must contain unique values.

B、cannot be CAST to other data types.

C、is created using the CREATE DISTINCT command.

D、contains a value that was automatically calculated from values in other columns.

You need to ensure that the database users should be able to use the various flashback query features in order to go back in time by four hours. What would you do to achieve this?（）

set SQL_TRACE=True 

set UNDO_RETENTION=14400 

set FAST_START_MTTR_TARGET=240 

set LOG_CHECKPOINT_INTERVAL=240 

set DB_FLASHBACK_RETENTION_TARGET=14400 

set the RETENTION GUARANTEE clause for the undo tablespace

打开工作簿文件EXC.xlsx（内容同第2套电子表格题（2）中的EXC.xlsx文件），对工作表“选修课程成绩单”内的数据清单的内容进行分类汇总（提示：分类汇总前先按主要关键字“课程名称”升序排序），分类字段为“课程名称”，汇总方式为“平均值”，汇总项为“成绩”，汇总结果显示在数据下方，将执行分类汇总后的工作表还保在EXC.xlsx工作簿文件中，工作表名不变。