Leap Year Check

This is a quick SQL statement to check if a year is a leap year:

SELECT :YEAR,
       DECODE (MOD (:YEAR, 4), 0, DECODE (MOD (:YEAR, 400), 0, 1, DECODE (MOD (:YEAR, 100), 0, 0, 1)), 0) AS leap_year
FROM   DUAL;

The above SQL returns 1 if :YEAR is a leap year. Else, returns 0.