Which are the prerequisites for performing flashback transactions on your database？（） Undo retention guarantee for the database must be configured.。 Supplemental log must be enabled for the primary key.。 Supplemental log must be enabled.。 Execute permission on the DBMS_FLASHBACK package must be granted to the user.。
厂商（）市场中能够以最有效率的方式进行生产并能够使消费者得到最大满足。 完全垄断。 寡头垄断。 完全竞争。 垄断竞争。
You have only two redo log groups and these groups get overwritten several times in a day. Your database operates in NOARCHIVELOG mode and user-managed consistent backups are performed every Sunday night. On Thursday morning， you find that an important table has been dropped and purged. With reference to this scenario， up to what point in time can the data be recovered？（） until Thursday morning。 until that point in time when the database is opened。 until that point in time when the recovery is performed。 until last Sunday’s backup。 until that point in time when the table is dropped and purged。 until Wednesday evening。
移动通信基站天线应在防雷装置的保护范围内，防雷装置应设置专用雷电流引下线，材料应采用（）的热镀锌扁钢或者不小于35mm2铜导线。 40mmx4mm。 40mmx1mm。 40mmx2mm。 40mmx3mm。
You find today’s performance of your production database to be the best ever. Therefore， you want to be notified in the future whenever the performance degrades by 10% of today’s performance. What is the first step that you would take to ensure this？（） A。 B。 C。 D。 E。
关于人身安全保护令的说法正确的是（）。
