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