Calculate age from HIREDATE to system date of your computer
SELECT HIREDATE||' '||SYSDATE||' ' ||
TRUNC(MONTHS_BETWEEN(SYSDATE,HIREDATE)/12) ||' YEARS '||
TRUNC((MONTHS_BETWEEN(SYSDATE,HIREDATE))-(TRUNC(MONTHS_BETWEEN(SYSDATE,HIREDATE)/12)*12))||
'MONTHS' AS "AGE " FROM EMP;