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;