Starting/Stopping a Pluggable Database

From Root Container:
To change the open mode of a pluggable database from the root container, do as follows:
$ sqlplus / as sysdba
SQL> alter pluggable database salespdb open;
You can also start a pluggable database in a particular state, such as read-only:
SQL> startup pluggable database salespdb open read only;
To close a pluggable database, you can specify the name of the pluggable database:
SQL> alter pluggable database salespdb close immediate;
You can also open or close all pluggable databases while connected to the root container as SYS:
SQL> alter pluggable database all open;
SQL> alter pluggable database all close immediate;
From Pluggable:
To open/start a pluggable database, connect to the pluggable database as SYS:
$ sqlplus sys/foo@salespdb as sysdba
SQL> startup;
To shut down the database, issue the following command:
SQL> shutdown immediate;
Pluggable database architecture:
Oracle 12cR1 Optimal Flexible Architecture:
Oracle 12c Database Architecture: