Determine number of seconds in one year

Question

什么SQL表达式可以计算任何特定年份的秒数？

Answer 1

For non leap years:

SELECT 365 * 24 * 60 * 60 AS secInYear
FROM dual

And in general:

SqlFiddleDemo

SELECT
  24 * 60 * 60 * (
  CASE 
    WHEN MOD(EXTRACT(YEAR FROM sysdate), 400) = 0 
         OR ( MOD(EXTRACT(YEAR FROM sysdate), 4) = 0 AND MOD(EXTRACT(YEAR FROM sysdate), 100) != 0) THEN 366
    ELSE 365
  END ) AS secInYear
FROM dual

Answer 2

SELECT
    (ADD_MONTHS(TRUNC(SYSDATE, 'YYYY'), 12) - TRUNC(SYSDATE, 'YYYY')) * 86400 SECONDS
FROM
    DUAL;

Answer 3

SELECT DAYOFYEAR('2015-12-31') * 24 * 60 * 60 FROM DUAL

DAYOFYEAR将在正常年份的除夕返回365，在leap年返回366。