Question

I am using Oracle DB and trying to find the date difference in years.
I googled and find out I can use DateDiff function.
When I am using this function:

select datediff(year, date_1, date_2) as Age_Diff 
 from employee

I am getting an error

ORA-00904: "DATEDIFF": invalid identifier.

Please suggest what is wrong in this.

Answer 1

DATEDIFF is not a function that exists in Oracle.

What, exactly, does it mean to you to get a difference between two dates in years? For example, if you are given dates of 2010-04-01 and 2012-01-01, what is the expected output? The difference is 1 year and 9 months so would that be 1.75? Or should we count the number of days in those 9 months vs. the number of days in a year and divide the answer to get something slightly different than 1.75?

My first guess is that you want

SELECT months_between( date_1, date_2 )/12 years_between
  FROM employee

If you want to ignore any fractional part of a year

SELECT floor( months_between( date_1, date_2 )/12) floor_years_between
  FROM employee