Oracle SQL , how to use current date - a specified date

Question

For getting current date i use this..

select extract(year from sysdate) from dual;

For getting the date that my database hold i use this..

select extract(year from startdate) from staff;

But now i am trying to update a field call serviceYears inside staff, by using

current year - year of start date

to get the amount of years the staff have committed to work. how do i achieve it..

i am using oracle sql

Thanks!

I tried to use

SQL> select dual.sysdate-staff.startdatefrom dual,staff;

select dual.sysdate-staff.startdatefrom from dual,staff
            *
ERROR at line 1:
ORA-01747: invalid user.table.column, table.column, or column specification

I also tried

select SYSDATE-to_date('01-jan-2007','dd-mon-yyyy') from dual;

But it return me
SYSDATE-TO_DATE('01-JAN-2007','DD-MON-YYYY')
--------------------------------------------
                                  2136.93719

How do i just get the year?

Answer 1

You can do this

UPDATE STAFF
SET serviceYear = ROUND((sysdate - startDate)/365)

Ex:

select ROUND((sysdate - to_date('01-JAN-2007','DD-MON-YYYY'))/365) 
from dual; -- returns 6


select ROUND((sysdate - to_date('01-JAN-2005','DD-MON-YYYY'))/365,2) 
from dual; -- returns 7.85

Updated:

SELECT 
FLOOR((SYSDATE - TO_DATE('01-JAN-2005','DD-MON-YYYY'))/365) YEARDOWN,
CEIL((SYSDATE - TO_DATE('01-JAN-2005','DD-MON-YYYY'))/365) YearUP
FROM DUAL;

Answer 2

you do not need dual.sysdate - you can just reference sysdate.

select sysdate-staff.startdatefrom from staff