Create View with 365 days - oracle

Question

How to Create a View with all days in year. view should fill with dates from JAN-01 to Dec-31. How can I do this in Oracle ?
If current year have 365 days,view should have 365 rows with dates. if current year have 366 days,view should have 366 rows with dates. I want the view to have a single column of type DATE.

Answer 1

This simple view will do it:
create or replace view year_days as
select trunc(sysdate, 'YYYY') + (level-1) as the_day
from dual
connect by level <= to_number(to_char(last_day(add_months(trunc(sysdate, 'YYYY'),11)), 'DDD'))
/
Like this:
SQL> select * from year_days;
THE_DAY
---------
01-JAN-11
02-JAN-11
03-JAN-11
04-JAN-11
05-JAN-11
06-JAN-11
07-JAN-11
08-JAN-11
09-JAN-11
10-JAN-11
11-JAN-11
...
20-DEC-11
21-DEC-11
22-DEC-11
23-DEC-11
24-DEC-11
25-DEC-11
26-DEC-11
27-DEC-11
28-DEC-11
29-DEC-11
30-DEC-11
31-DEC-11
365 rows selected.
SQL>
The date is generated by applying several Oracle date functions:
trunc(sysdate, 'yyyy') gives us the first of January for the current year
add_months(x, 11) gives us the first of December
last_day(x) gives us the thirty-first of December
to_char(x, 'DDD') gives us the number of the thirty-first of December, 365 this year and 366 next.
This last figure provides the upper bound for the row generator CONNECT BY LEVEL <= X

Answer 2

you can use piplined table, it should be something like this:
create or replace type year_date_typ as object (v_day date);
create or replace type year_date_tab as table of year_date_typ;
CREATE OR REPLACE FUNCTION get_dates(year IN VARCHAR2) RETURN year_date_tab PIPELINED IS
v_start_date date := to_date('0101' || year, 'ddmmyyyy');
res year_date_typ := year_date_typ(null);
v_days_in_year integer := 365;
BEGIN
if to_char(last_day(to_date('0102'||year, 'ddmmyyyy')), 'dd') = '29' then
v_days_in_year := 366;
end if;
FOR i in 0 .. v_days_in_year integer-1 LOOP
res.v_day := v_start_date + i;
pipe row(res);
END LOOP;
return;
END get_dates;
and you can use it:
select * from table(get_dates('2011'));

Answer 3

This works well in MS SQL
SELECT TOP (DATEDIFF(day, DATEADD(yy, DATEDIFF(yy,0,getdate()), 0), DATEADD(yy, DATEDIFF(yy,0,getdate()) + 1, -1))) n = ROW_NUMBER() OVER (ORDER BY [object_id]),
dateadd(day, ROW_NUMBER() OVER (ORDER BY [object_id]) - 1, DATEADD(yy, DATEDIFF(yy,0,getdate()), 0)) AS AsOfDate FROM sys.all_objects