query the database for the user’s information

If you want to obtain environment and session information such as the name and IP address of the
current user so that the values can be stored into local variables for logging purposes you can make use of the SYS_CONTEXT built-in function to query the database for the user’s information. Once you
have obtained the information, then store it into a local variable. At that point, you can do whatever
you’d like with it, such as save it in a logging table.

DECLARE
  username      varchar2(100);
  ip_address    varchar2(100); 

BEGIN
  SELECT SYS_CONTEXT('USERENV','SESSION_USER'), SYS_CONTEXT('USERENV','IP_ADDRESS')
  INTO username, ip_address
  FROM DUAL;

  DBMS_OUTPUT.PUT_LINE('The connected user is: ' || username || ', and the IP address
 is ' ||
                                                      ip_address);
END;