Resolved: Rollback clause does not retrieve the last change

Hi Dear, You Are Very Nice and Professional. Thanks a bunch!!

First step:
I create new table as following:

CREATE TABLE departments_dup (
    dept_no CHAR(4) NOT NULL,
    dept_name VARCHAR(255) NOT NULL
);

Second step:
copy all depatments table to new table

INSERT INTO departments_dup
SELECT * FROM departments;

3st step: Commit;
4st step: run update clause and change all rows to the following
UPDATE departments_dup
SET
    dept_no = 'd010',
    dept_name = 'Quality Manager'

5st: rollback;
but i can not retrive first data