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.
若两台主机在同一子网中,则两台主机的IP地址分别与它们的子网掩码相“与”的结果一定()。
A、为全0
B、为全1
C、相同
D、不同
Which three statements correctly describe the features of the I/O calibration process?()
AOnly one I/O calibration process can run at a time.
BIt automates the resource allocation for the Automated Maintenance Tasks.
CIt improves the performance of the performance-critical sessions while running.
DIt can be used to estimate the maximum number of I/Os and maximum latency time for the system.
EThe latency time is computed only when the TIMED_STATISTICS initialization parameter is set to TRUE.
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。
如果文件系统中有两个文件重名,不应采用()。
A、单级目录结构
B、树型目录结构
C、二级目录结构
D、A和C
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