primary database convert to physical standby

Accidentally primary database convert to physical standby  Don't worry there is a solution






SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.

Total System Global Area  313860096 bytes
Fixed Size                  1299624 bytes
Variable Size             285215576 bytes
Database Buffers           20971520 bytes
Redo Buffers                6373376 bytes
Database mounted.
SQL> alter database convert to physical standby;

Database altered.
SQL> alter database convert to primary database;
alter database convert to primary database
                          *
ERROR at line 1:
ORA-00922: missing or invalid option

SQL> alter database activate standby database;

Database altered.

SQL> alter database open;

Database altered.

SQL> select database_role from v$database;

DATABASE_ROLE
----------------
PRIMARY