单项选择题 Inyourdatabaseinstance，theusersessionsareconnectedtothedatabaseserverfromtheremotemachines.Youwanttoachievethefollowingfortheseusers： 1.Theuseraccountmustbelockedafterfourunsuccessfulloginattempts. 2.Theusermustbepromptedtochangethepasswordatregularintervals. 3.Theusermaynothavemorethanthreesimultaneoussessions. 4.Theusersessionmustautomaticallybeloggedoffifmorethan10minuteselapsedtimeused. Howwouldyouaccomplishtheabove（）

单项选择题 Note the following points describing various utilities in Oracle Database 1g：1. It enables the high-speed transfer of data from one database to another. 2. It provides a complete solution for the backup， restoration， and recovery needs of the entire database.3. It enables the loading of data from an external file into an Oracle database.4. It provides a tape backup management for the Oracle ecosystem. Which point describes Oracle Secure Backup（）

单项选择题 You executed the following command to perform a backup of the USERS tablespace：SQL> ALTER TABLESPACE users BEGIN BACKUP；ALTER TABLESPACE users BEGIN BACKUP* ERROR at line 1： ORA-01123： cannot start online backup； media recovery not enabled What could be the reason for this error（）