Oracle Database 11g The Complete Reference (Osborne ORACLE ...

182 Part II: SQL and SQL *Plus
29-FEB-04
31-MAR-04
30-APR-04
31-MAY-04
30-JUN-04
31-JUL-04
31-AUG-04
30-SEP-04
31-OCT-04
30-NOV-04
31-DEC-04
MONTHS_BETWEEN Two Dates
You recently came across a file containing the birthdates of a group of friends. You load the
information into a table called BIRTHDAY and display it:
select FirstName, LastName, BirthDate from BIRTHDAY;
FIRSTNAME LASTNAME BIRTHDATE
--------------- --------------- ---------
GEORGE SAND 12-MAY-46
ROBERT JAMES 23-AUG-37
NANCY LEE 02-FEB-47
VICTORIA LYNN 20-MAY-49
FRANK PILOT 11-NOV-42
To calculate each person’s age, compute the months between today’s date and their birth dates,
and divide by 12 to get the years. The division will print the age with a decimal component.
Because most people over the age of 7 don’t report their age using portions of years, apply a
FLOOR function to the computation.
select FirstName, LastName, BirthDate,
FLOOR(
MONTHS_BETWEEN(SysDate,BirthDate)/12
) AS Age
from BIRTHDAY;
FIRSTNAME LASTNAME BIRTHDATE AGE
--------------- --------------- --------- -------
GEORGE SAND 12-MAY-46 61
ROBERT JAMES 23-AUG-37 70
NANCY LEE 02-FEB-47 61
VICTORIA LYNN 20-MAY-49 58
FRANK PILOT 11-NOV-42 65
Combining Date Functions
You are hired on February 28, 2008, at a great new job, with a starting salary that is lower than
you had hoped, but with a promise of a review the first of the month after six months have
passed. If the current date is February 28, 2008, when is your review date?