Manage Password expiration via Profile in Oracle

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General
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Make user password never expire:

SELECT username, profile, expiry_date 
  FROM DBA_USERS;

ALTER PROFILE DEFAULT LIMIT PASSWORD_REUSE_TIME UNLIMITED;
ALTER PROFILE DEFAULT LIMIT PASSWORD_LIFE_TIME  UNLIMITED;


Users that were already expired, will not be affected by above statements, need to unlock them, and reset their password.
Only then the password expiration_date becomes NULL;


ALTER USER XXX IDENTIFIED BY YYY;