问题
I want to get total number of days between two provided dates. I've tried the below query but didn't get the exact different; the last date is not being included.
select (to_date ('15-06-13','dd-MM-yyyy') - to_date('01-02-12','dd-MM-yyyy'))
from dual
This should return 501 days but it is returning 500 days instead. If I add +1 after calculation, then I'm getting the correct result.
Do I really need to include +1 or is there an alternate approach to get the actual result?
回答1:
In Oracle substracting two dates returns the number of days between two dates.
A minus operator works in the same way as for numbers:
20 - 20 = 0 ===> 2013-05-20 - 2013-05-20 = 0
25 - 20 = 5 ===> 2013-05-25 - 2013-05-20 = 5
If you want to include last number or last date, you need to add 1:
20 - 20 + 1 = 1 ===> 2013-05-20 - 2013-05-20 + 1 = 1
25 - 20 + 1 = 6 ===> 2013-05-25 - 2013-05-20 + 1 = 6
来源：https://stackoverflow.com/questions/20721413/get-the-number-of-days-between-two-dates-in-oracle-inclusive-of-the-dates