Pluggable databases (PDBS)

 select * from v$pdbs;

alter pluggable database all open;

alter pluggable database pdb_name save state;

alter pluggable database all save state ;

SQL> show pdbs;
    CON_ID CON_NAME            OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 PDB                                   READ WRITE NO

ALTER PLUGGABLE DATABASE pdb$seed,pdb OPEN READ ONLY FORCE;
ALTER PLUGGABLE DATABASE pdb$seed,pdb CLOSE IMMEDIATE;
ALTER PLUGGABLE DATABASE ALL OPEN;
ALTER PLUGGABLE DATABASE ALL CLOSE IMMEDIATE;
ALTER PLUGGABLE DATABASE ALL EXCEPT pdb$seed OPEN;
ALTER PLUGGABLE DATABASE ALL EXCEPT pdb CLOSE IMMEDIATE;

startup force;

startup open read write;

startup open read only;

startup upgrade;

shutdown immediate;

shutdown abort;