SQL: Structured Query Language - Oracle 10g Database Administration Concepts and Implementation Made Simple - page 29

Example:
SELECT SYSDATE,
LAST_DAY(SYSDATE) "Last",
LAST_DAY(SYSDATE) - SYSDATE "Days Left"
FROM DUAL;
Output:
SYSDATE Last Days Left
--------- --------- ----------
23-OCT-97 31-OCT-97 8
Example:
SELECT MONTHS_BETWEEN(SYSDATE, hiredate)
“Months of Service"
FROM DUAL;
Example:
SELECT ROUND (TO_DATE ('27-OCT-92'),'YEAR')
"New Year" FROM DUAL;
Output:
New Year
---------
01-JAN-93
Example:
SELECT TRUNC(TO_DATE('27-OCT-92','DD-MON-
YY'), 'YEAR')
"New Year" FROM DUAL;