SELECT ename, HIREDATE "HDATE", (HIREDATE + interval '10' day)"H10" FROM emp where rownum < 7

postgresql:

SELECT ename, HIREDATE "HDATE", DATE(HIREDATE + 10) FROM emp limit 6

MySQL

SELECT ename, HIREDATE "HDATE", DATE(HIREDATE + 10) FROM emp limit 6