1.  Create an 'AFTER INSERT' Trigger   
SQL> -- create demo table
SQL> create table Employee(
  2    ID                 VARCHAR2(4 BYTE)         NOT NULL,
  3    First_Name         VARCHAR2(10 BYTE),
  4    Last_Name          VARCHAR2(10 BYTE),
  5    Start_Date         DATE,
  6    End_Date           DATE,
  7    Salary             Number(8,2),
  8    City               VARCHAR2(10 BYTE),
  9    Description        VARCHAR2(15 BYTE)
 10  )
 11  /

Table created.

SQL>
SQL>
SQL> --  AFTER INSERT Trigger
SQL>
SQL>
SQL>     CREATE OR REPLACE TRIGGER employee_after_insert
  2      AFTER INSERT
  3          ON employee
  4          FOR EACH ROW
  5
  6      DECLARE
  7          v_username varchar2(10);
  8
  9      BEGIN
 10          -- Find username of person performing the INSERT into the table
 11          SELECT user INTO v_username
 12          FROM dual;
 13
 14          dbms_output.put_line('By: '||v_username);
 15          dbms_output.put_line(':new.id: '||:new.id);
 16          dbms_output.put_line(':new.first_name: '||:new.first_name);
 17          dbms_output.put_line(':new.last_name: '||:new.last_name);
 18          dbms_output.put_line(':old.id: '||:old.id);
 19          dbms_output.put_line(':old.first_name: '||:old.first_name);
 20          dbms_output.put_line(':old.last_name: '||:old.last_name);
 21      END;
 22      /

Trigger created.

SQL>
SQL> -- prepare data
SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2               values ('01','Jason',    'Martin',  to_date('19960725','YYYYMMDD'), to_date('20060725','YYYYMMDD'), 1234.56, 'Toronto',  'Programmer')
  3  /
By: JAVA2S
:new.id: 01
:new.first_name: Jason
:new.last_name: Martin
:old.id:
:old.first_name:
:old.last_name:

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('02','Alison',   'Mathews', to_date('19760321','YYYYMMDD'), to_date('19860221','YYYYMMDD'), 6661.78, 'Vancouver','Tester')
  3  /
By: JAVA2S
:new.id: 02
:new.first_name: Alison
:new.last_name: Mathews
:old.id:
:old.first_name:
:old.last_name:

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('03','James',    'Smith',   to_date('19781212','YYYYMMDD'), to_date('19900315','YYYYMMDD'), 6544.78, 'Vancouver','Tester')
  3  /
By: JAVA2S
:new.id: 03
:new.first_name: James
:new.last_name: Smith
:old.id:
:old.first_name:
:old.last_name:

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('04','Celia',    'Rice',    to_date('19821024','YYYYMMDD'), to_date('19990421','YYYYMMDD'), 2344.78, 'Vancouver','Manager')
  3  /
By: JAVA2S
:new.id: 04
:new.first_name: Celia
:new.last_name: Rice
:old.id:
:old.first_name:
:old.last_name:

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('05','Robert',   'Black',   to_date('19840115','YYYYMMDD'), to_date('19980808','YYYYMMDD'), 2334.78, 'Vancouver','Tester')
  3  /
By: JAVA2S
:new.id: 05
:new.first_name: Robert
:new.last_name: Black
:old.id:
:old.first_name:
:old.last_name:

1 row crea