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;
--