Delete duplicate values from a table

DELETE FROM my_table
WHERE ROWID NOT IN (SELECT MIN(ROWID)
                       FROM my_table
                      GROUP BY delete_col_name);

-- Example :
--
-- Given a table called emp with the following columns:
--   id   number
--   name varchar2(20)
--   sal  number
--
-- To delete the duplicate values:
--
-- DELETE FROM emp
--  WHERE ROWID NOT IN (SELECT MIN(ROWID) FROM emp GROUP BY id);
--
-- COMMIT;
--