SQL> SELECT TO_CHAR(STANDBY_BECAME_PRIMARY_SCN) FROM V$DATABASE;

TO_CHAR(STANDBY_BECAME_PRIMARY_SCN)

----------------------------------------

SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';

Session altered.

SQL> select oldest_flashback_scn,oldest_flashback_time from v$flashback_database_log;

OLDEST_FLASHBACK_SCN OLDEST_FLASHBACK_TI

-------------------- -------------------

    1202090 2019-05-05 04:01:45

SQL> recover managed standby database cancel;

Media recovery complete.

SQL> 

SQL> 

SQL> recover managed standby database finish force;

Media recovery complete.

SQL> select database_role from v$database;

DATABASE_ROLE

----------------

PHYSICAL STANDBY

SQL> select open_mode,database_role,protection_mode,protection_level,switchover_status from v$database;

OPEN_MODE      DATABASE_ROLE    PROTECTION_MODE    PROTECTION_LEVEL  SWITCHOVER_STATUS

-------------------- ---------------- -------------------- -------------------- --------------------

READ ONLY      PHYSICAL STANDBY MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE  TO PRIMARY

SQL> alter database commit to switchover to primary;

Database altered

SQL> 

SQL> select open_mode,database_role,protection_mode,protection_level,switchover_status from v$database;

OPEN_MODE      DATABASE_ROLE    PROTECTION_MODE    PROTECTION_LEVEL  SWITCHOVER_STATUS

-------------------- ---------------- -------------------- -------------------- --------------------

MOUNTED      PRIMARY       MAXIMUM PERFORMANCE  UNPROTECTED  NOT ALLOWED

SQL> SELECT TO_CHAR(STANDBY_BECAME_PRIMARY_SCN) FROM V$DATABASE;

TO_CHAR(STANDBY_BECAME_PRIMARY_SCN)

----------------------------------------

1330559

SQL> alter database open;

Database altered.

SQL> select open_mode,database_role,protection_mode,protection_level,switchover_status from v$database;

OPEN_MODE      DATABASE_ROLE    PROTECTION_MODE    PROTECTION_LEVEL  SWITCHOVER_STATUS

-------------------- ---------------- -------------------- -------------------- --------------------

READ WRITE      PRIMARY       MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE  NOT ALLOWED

SQL> SELECT TO_CHAR(STANDBY_BECAME_PRIMARY_SCN) FROM V$DATABASE;

TO_CHAR(STANDBY_BECAME_PRIMARY_SCN)

----------------------------------------

1330559

SQL>