Oracle user accounts can be locked, unlocked, forced to choose new
passwords, etc. For example, all accounts except SYS and SYSTEM will
be locked after creating an Oracle9iDB database using the DB Configuration Assistant (dbca). DBA's must unlock these accounts to
make them available to users.
Look at these examples:
ALTER USER scott ACCOUNT LOCK -- lock a user account
ALTER USER scott ACCOUNT UNLOCK; -- unlocks a locked users
account
ALTER USER scott PASSWORD EXPIRE; -- Force user to choose a new
password