简述对语言“约定俗成”性的理解。
You are performing a block media recovery on the tools01.dbf data file in the SALES database by using RMAN. Which two statements are correct in this scenario？（） You must ensure that the SALES database is mounted or open.。 You must restore a backup control file to perform a block media recovery.。 You must take the tools01.dbf data file offline before you start a block media recovery.。 You must put the database in NOARCHIVELOG mode to perform a block media recovery.。 You can perform only a complete media recovery of individual blocks； point-in-time recovery of individual data blocks is not supported.。
举例说明影响员工报酬水平的主要因素
内源性污染
You are managing the APPPROD database as a DBA. You plan to duplicate this database in the same system with the name DUPDB. You issued the following RMAN commands to create a duplicate database: Which three are the prerequisites for the successful execution of the above command?（） The source database should be open。 The target database should be in ARCHIVELOG mode if it is open。 RMAN should be connected to both the instances as SYSDBA。 The target database backups should be copied to the source database backup directories。 The password file must exist for the source database and have the same SYS user password as the target。
A storage specialist is assessing a customer’s tape backup environment. Which of the following questions would be the most appropriate question to identify the customer’s environment？（）
