多项选择题
A. Open the database in read-only mode.
B. Set the retention target with the DB_FLASHBACK_RETENTION_TARGET initialization parameter.
C. Enable the block change tracking feature.
D. Execute the ALTER DATABASE FLASHBACK ON statement.
单项选择题 You dropped a schema of a user in an Oracle 10g by mistake. You decide to flash the database back to its previous state to restore the deleted schema. Which process writes the before images of the physical database blocks to the flashback database logs？（）
单项选择题 Youarerequiredtoflashbackyourdatabase.Youwanttofindtheamountofflashbackdatageneratedsincethedatabasewasopened.Whichtaskwillyouperformtoobtaintherequiredinformation？（）
多项选择题 In which two scenarios should you issue the following command？（） FLASHBACK TABLE SCOTT.EMP TO TIMESTAMP SYSTIMESTAP- INTERVAL ’15’ MINUTE；