Is this what you mean?
drop table if exists employee;
create table employee (
id int primary key,
first_name varchar(200),
last_name varchar(15),
start_date date,
end_date date ,
salary decimal(8,2),
city varchar(10) ,
description varchar(15)
);
CREATE TRIGGER HASHPASSWORD_PARENT BEFORE INSERT ON employee
FOR EACH ROW SET NEW.first_name = MD5(NEW.first_name);
insert into employee values
(1, 'lokesh', 'Martin', '1996-07-25', '2006-07-25', 600.00, 'Toronto', 'Programmer'),
(2, 'chris', 'Mathews', '1976-03-21', '1986-02-21', 600.00, 'Vancouver', 'Tester' ),
(3, 'loknath', 'VARMA', '1976-03-21', '1986-02-21', 600.00, 'Vancouver', 'Tester' ),
(4, 'kumar', 'MOHAN', '1976-03-21', '1986-02-21', 600.00, 'Vancouver', 'Tester' );
select id,first_name from employee;
+----+----------------------------------+
| id | first_name |
+----+----------------------------------+
| 1 | 5f0e353b1c01e95c08233f477bf4f945 |
| 2 | 6b34fe24ac2ff8103f6fce1f0da2ef57 |
| 3 | 727b8b8a7274be87cfadb7e641147398 |
| 4 | 79cfac6387e0d582f83a29a04d0bcdc4 |
+----+----------------------------------+
For MySQL Trigger syntax see the MySQL manual page for Triggers.
PB