If you back up a database without connecting to the recovery catalog， which operations will cause the recovery catalog to be updated？（） [" The next time you back up the database when you are also connected to the recovery catalog and the target database"," The next time you are connected to the target database and the recovery catalog database and issue the resync command"," The next time you connect RMAN to just the recovery catalog"," The next time you connect to the recovery catalog and the target database with RMAN"," Connecting to the recovery catalog and issuing the resync all databases command"]
下列不属于隐性广告表现形式的是（） ["网络新闻广告","BBS广告","搜索广告","全屏广告"]
Why would you use the following FLASHBACK TABLE command？（） FLASHBACK TABLE emp TO TIMESTAMP （’11：45’，’hh12：mi’）； ["to undo the changes made to the EMP table since the specified time","to restore the EMP table that was wrongly dropped from the database","to view the transactions that have modified the EMP table since the specified time","to view the changes made to the EMP table for one or more rows since the specified time","to recover the EMP table to a point in time in the past by restoring the most recent backu"]
杜朗口三三六模式主要含义是什么？
A subquery can be used to （）. [" Create groups of data"," Sort data in a specific order"," Convert data to a different format"," Retrieve data based on an unknown conditio"]
一般情况下，输电距离越大，所用的电压等级越高，其原因是（）。
