Syntax for switching over a container database using data guard broker

Here I am switching over a container database called cdb, to the standby server which is running a container database with unique name cdb_stby1.

First, view the configuration:

DGMGRL> show configuration

Configuration - DGConfig1

  Protection Mode: MaxPerformance
  Members:
  cdb       - Primary database
    cdb_stby1 - Physical standby database

Fast-Start Failover:  Disabled

Configuration Status:
SUCCESS   (status updated 84 seconds ago)

Perform the switchover:

DGMGRL> switchover to 'cdb_stby1';

Typical output from a successful switchover:

Performing switchover NOW, please wait...
Operation requires a connection to database "cdb_stby1"
Connecting ...
Connected to "cdb_stby1"
Connected as SYSDBA.
New primary database "cdb_stby1" is opening...
Operation requires start up of instance "cdb" on database "cdb"
Starting instance "cdb"...
Connected to an idle instance.
ORACLE instance started.
Connected to "cdb"
Database mounted.
Switchover succeeded, new primary is "cdb_stby1"

If I wish to switch back, make sure you log on to whichever server is running your primary database at the time.
(DO NOT use os authentication with dgmgrl / as sysdba, it will throw an error)

dgmgrl sys@cdb_stby1 as sysdba
DGMGRL for Linux: Release 19.0.0.0.0 - Production on Thu Sep 7 15:27:27 2023
Version 19.20.0.0.0

Copyright (c) 1982, 2019, Oracle and/or its affiliates.  All rights reserved.

Welcome to DGMGRL, type "help" for information.
Password:
Connected to "cdb_stby1"
Connected as SYSDBA.
DGMGRL> show configuration;

Configuration - DGConfig1

  Protection Mode: MaxPerformance
  Members:
  cdb_stby1 - Primary database
    cdb       - Physical standby database

Fast-Start Failover:  Disabled

Configuration Status:
SUCCESS   (status updated 46 seconds ago)

DGMGRL> switchover to cdb
Performing switchover NOW, please wait...
Operation requires a connection to database "cdb"
Connecting ...
Connected to "cdb"
Connected as SYSDBA.
New primary database "cdb" is opening...
Operation requires start up of instance "cdb" on database "cdb_stby1"
Starting instance "cdb"...
Connected to an idle instance.
ORACLE instance started.
Connected to "cdb_stby1"
Database mounted.
Switchover succeeded, new primary is "cdb"