SQL> CREATE TABLE t (n1 NUMBER, n2 NUMBER <font color=red>DEFAULT 33</font>);
  
Table created.
  
SQL> SELECT utc.column_name
  2  ,      utc.data_default
  3  FROM   sys.user_tab_columns   utc
  4  WHERE  utc.table_name = 'T'
  5  /
  
COLUMN_NAME                    DATA_DEFAULT
------------------------------ ----------------------------------------
N1
N2                             <font color=red>33</font>
  
SQL>

CREATE OR REPLACE PROCEDURE update_emails
BEGIN
    UPDATE t
    SET    t.email = t.user_id || '@hotmail.com'
    WHERE  t.user_id IS NOT NULL;
    COMMIT;
END update_emails;