SQL> select OPEN_MODE,PROTECTION_MODE,PROTECTION_LEVEL,SWITCHOVER_STATUS from v$
database;OPEN_MODE            PROTECTION_MODE      PROTECTION_LEVEL
-------------------- -------------------- --------------------
SWITCHOVER_STATUS
--------------------
READ WRITE           MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE
FAILED DESTINATION
今天打开数据库查了一下,发现SWITCHOVER_STATUS为FAILED DESTINATION,请问是怎么回事,怎么改才能变成to standby?