Getting the next valid date (jump holidays and weekends)

Question

Hello,
I have a column table where I have all holidays of the year in the format "yyyymmdd,yyyymmdd,...", for example, "20091012,20091225".
I'd like to do a query where I pass a date and a increment of days and it returns the next valid date, excluding weekends and the holidays that I have in the column holidays that I show above.
P.S: Instead of pass a date and a increment of days, I could pass just a already incremented date, and this query just validate this date, adding 2 days for each weekend and one day for each holiday.
Is there a way to do that?
Thanks

Answer 1

Hi,
Ranieri wrote:
Hello,
I have a column table where I have all holidays of the year in the format "yyyymmdd,yyyymmdd,...", for example, "20091012,20091225".Dates should always be stored in DATE columns. If you really want to, your can also store the formatted date in a separate column.
I'd like to do a query where I pass a date and a increment of days and it returns the next valid date, excluding weekends and the holidays that I have in the column holidays that I show above.For convenience, you can't beat a user-defined function, such as Etbin's.
If you really want a pure SQL solution, you can
(a) generate a list of all the days that might be between the start date and end date (sub-query all_days below)
(b) outer join that to your holiday table (sub-query got_dnum, below)
(c) rule out the holidays and weekends (sub_query got_dnum, WHERE clause)
(d) return the nth remaining day (main query below)
WITH     all_days     AS
     SELECT  TO_DATE (:start_date, 'DD-Mon-YYYY') + LEVEL     AS dt
     FROM     dual
     CONNECT BY     LEVEL <= 3           -- 3 = max. consecutive non-work days
               + (:day_cnt * 7 / 4)     -- 4 = min. work days per week
,     got_dnum     AS
     SELECT     a.dt
     ,     ROW_NUMBER () OVER (ORDER BY a.dt)     AS dnum
     FROM          all_days     a
     LEFT OUTER JOIN     holidays     h     ON     a.dt = TO_DATE (txt, 'YYYYMMDD')
     WHERE     h.txt               IS NULL
     AND     TO_CHAR (a.dt, 'Dy')      NOT IN ('Sat', 'Sun')
SELECT     dt
FROM     got_dnum
WHERE     dnum     = :day_cnt
;This assumes :day_cnt > 0.
The tricky part is estimating how far you might have to go in sub-query all-days to be certain you've included at leas :day_cnt work days.
Where I work, holidays are always at least 7 days apart.
That means that there can be, at most, 3 consective days without work (which happens when there is a holiday on Monday or Friday), and that thee are at least 4 work days in any period of 7 consecutive days. That's where the "magic numbers" 3 and 4 come from in the CONNECT BY clause of all_days. Depending on your holidays, you may need to change those numbers.
P.S: Instead of pass a date and a increment of days, I could pass just a already incremented date, and this query just validate this date, adding 2 days for each weekend and one day for each holiday.Good thought, but it won't quite work. How do you know how many holidays were in the interval? And what if the first step produces a Saturday before a Monday holioday?
You might be interested in [this thread|http://forums.oracle.com/forums/message.jspa?messageID=3350877#3350877]. Among other things, it includes a function for determining if a given date (in any year) is a holiday, without reference to a table.