-- https://docs.oracle.com/en/database/oracle/oracle-database/23/sqlrf/ALTER-DATABASE-LINK.html
ALTER DATABASE LINK private_link 
  CONNECT TO hr IDENTIFIED BY hr_new_password;
ALTER PUBLIC DATABASE LINK public_link
  CONNECT TO scott IDENTIFIED BY scott_new_password;
ALTER SHARED PUBLIC DATABASE LINK shared_pub_link
  CONNECT TO scott IDENTIFIED BY scott_new_password
  AUTHENTICATED BY hr IDENTIFIED BY hr_new_password;
ALTER SHARED DATABASE LINK shared_pub_link
  CONNECT TO scott IDENTIFIED BY scott_new_password;