PostgreSQL 에서 날짜의 덧셈 뺄셈은 다음과 같이 수행할수 있습니다.
오라클에서의 syntax 와 동일하네요.
scott@[local]:5432 scottdb#SQL> select hiredate,
hiredate - interval '2 day' ,
hiredate + interval '2 day' ,
hiredate - interval '2 month' ,
hiredate - interval '2 year'
from emp where deptno=20;
hiredate | ?column? | ?column? | ?column? | ?column?
------------+---------------------+---------------------+---------------------+---------------------
1980-12-17 | 1980-12-15 00:00:00 | 1980-12-19 00:00:00 | 1980-10-17 00:00:00 | 1978-12-17 00:00:00
1981-04-02 | 1981-03-31 00:00:00 | 1981-04-04 00:00:00 | 1981-02-02 00:00:00 | 1979-04-02 00:00:00
1982-12-09 | 1982-12-07 00:00:00 | 1982-12-11 00:00:00 | 1982-10-09 00:00:00 | 1980-12-09 00:00:00
1983-01-12 | 1983-01-10 00:00:00 | 1983-01-14 00:00:00 | 1982-11-12 00:00:00 | 1981-01-12 00:00:00
1981-12-03 | 1981-12-01 00:00:00 | 1981-12-05 00:00:00 | 1981-10-03 00:00:00 | 1979-12-03 00:00:00
scott@[local]:5432 scottdb#SQL>
이번에는 날짜 차를 구해볼까요?
scott@[local]:5432 scottdb#SQL> select smith_hiredate, allen_hiredate,
allen_hiredate - smith_hiredate
from (
select hiredate as smith_hiredate
from emp
where ename='SMITH'
) x,
(
select hiredate as allen_hiredate
from emp
where ename='ALLEN'
) y;
smith_hiredate | allen_hiredate | ?column?
----------------+----------------+----------
1980-12-17 | 1981-02-20 | 65
(1 row)
Time: 2.618 ms
scott@[local]:5432 scottdb#SQL>
