年月日總和 - Oracle SQL

Question

一年 = 365 天，一個月 = 31 天

Select 1 as year, 5 as month, 10 as day from dual
union all
Select 1 as year, 10 as month, 25 as day from dual

需要resault為：

years  month  day
3      4      4

Answer 1

如果 1 年 = 365 天，1 個月 = 31 天，則：

SELECT TRUNC(SUM(year*365 + month*31 + day)/365) AS years,
       TRUNC(MOD(SUM(month*31 + day), 365)/31) AS month,
       MOD(MOD(SUM(month*31 + day), 365), 31) AS day
FROM
(
  Select 1 as year, 5 as month, 10 as day from dual
  union all
  Select 1 as year, 13 as month, 25 as day from dual 
) t1;

哪個輸出：

年	月	天
3	7	11

---

如果 1 年 = 12 個月和 1 個月 = 31 天，那么你想要：

SELECT TRUNC(SUM(year + month/12 + day/31/12)) AS years,
       TRUNC(MOD(SUM(month + day/31), 12)) month,
       MOD(SUM(day) , 31) day
FROM
(
  Select 1 as year, 5 as month, 10 as day from dual
  union all
  Select 1 as year, 13 as month, 25 as day from dual 
) t1;

哪個輸出：

年	月	天
3	7	4

db<> 在這里擺弄

Answer 2

我們可以根據條件使用一些算法來計算天數

• one year = 365 days
• one month = 31 days

1. 年：（年 * 365 + 月 * 31 + 日）除以 365 得到數字的總年份。
2. Month : (month * 31 + day) 除以 31 得到總月份數，但我們需要從中獲取 mod，因為如果總月份數高於 12，則將攜帶總月份數。

作為這個查詢。

select CAST(SUM((year * 365 + month * 31 + day) / 365) AS INT) years  ,
       CAST(MOD(SUM(month * 31 + day)/31, 12) AS INT) month,
       MOD(SUM(day) , 31) day
from 
(
  Select 1 as year, 5 as month, 10 as day from dual
  union all
  Select 1 as year, 10 as month, 25 as day from dual 
) t1;

sqlfiddle