12c Containers

Working with PDBs
Set your ORACLE_SID and log into the CDB instance using normal oraenv and sqlplus "/ as sysdba" method.

Is current DB a CDB?

SQL> select cdb from v$database;
 
CDB
---
YES

- or -

SQL> show con_name

CON_NAME
------------------------------
PDB1

View available PDBs

SQL> SELECT name, open_mode FROM v$pdbs;

NAME                           OPEN_MODE
------------------------------ ----------
PDB1                           READ WRITE

- or -

SQL> show pdbs

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         3 PDB1                           READ WRITE NO

Startup a PDB, persist open state when CDB opens

ALTER PLUGGABLE DATABASE PDB_NAME OPEN;
SELECT name, open_mode FROM v$pdbs;
ALTER PLUGGABLE DATABASE PDB SAVE STATE;

Switch Container Databases

ALTER SESSION SET CONTAINER=CDB$ROOT;
SHOW CON_NAME

ALTER SESSION SET CONTAINER=PDB_NAME;
SHOW CON_NAME

References
Viewing Information About CDBs and PDBs with SQL*Plus