sql working days holidays - sql

Question

I've seen different version of this kind of function for other coding languages (Python, jQuery, etc.) but not for SQL. I have a procedure that needs to have a date calculated that is 65 days from the creation date, but it cannot include weekend or holidays. We already have a function that is able to add only working days to a date, but not take into account holidays. We have a holiday table that lists all the holiday dates, tblHolidayDates with a column HolidayDate in standard date format.
How would I do this? I'd also consider maybe just creating a Calendar table as well if someone could give me a CREATE TABLE query for that - all it would need is dates, weekday, and holiday columns.
Below I have given the current loop function that adds business days, but it's missing holidays. Any help would be greatly appreciated!!
ALTER FUNCTION [dbo].[AddWorkDaysToDate]
(
#fromDate datetime,
#daysToAdd int
)
RETURNS datetime
AS
BEGIN
DECLARE #toDate datetime
DECLARE #daysAdded integer
-- add the days, ignoring weekends (i.e. add working days)
set #daysAdded = 1
set #toDate = #fromDate
while #daysAdded <= #daysToAdd
begin
-- add a day to the to date
set #toDate = DateAdd(day, 1, #toDate)
-- only move on a day if we've hit a week day
if (DatePart(dw, #toDate) != 1) and (DatePart(dw, #toDate) != 7)
begin
set #daysAdded = #daysAdded + 1
end
end
RETURN #toDate
END

Answer 1

I wrote a SQL function years ago to build a dynamic holiday table as a table function. The link is below:
http://www.joebooth-consulting.com/sqlServer/sqlServer.html#CalendFunc
Hope it helps...
You can access the table function (or your own holiday table) to determine number of holidays via a SQL statement like below
SELECT count(*) FROM holiday_date(2013)
WHERE holiday_date BETWEEN #fromDate AND #toDate
then add the count to the returned date using dateAdd().
If you might have holidays that fall on a weekend, add the following to the WHERE clause
AND DatePart(dw, Holiday_date) != 1) and (DatePart(dw, holiday_date) != 7)

Answer 2

I've always achieved this with a static table of dates from roughly 5 years in the past to 10 in the future, each date being marked with 'working day' status and sometimes other flags as required. Previously using MS-SL server I would achieve this quickly with a WHILE loop, I think MySQL supports the same syntax
WHILE (condition)
BEGIN
INSERT date
END
To create the table either use the Enterprise Manager UI or something like
CREATE TABLE DateTable
(
actual_date datetime NOT NULL,
is_holiday bit NOT NULL
)

Answer 3

Assuming we have a DateTable with columns actual_date (date) and is_holiday (bit) , containing all dates and where all workdays have is_holiday=0:
SELECT actual_date from
(
SELECT actual_date, ROW_NUMBER() OVER(ORDER BY actual_date) AS Row
FROM DateTable
WHERE is_holiday= 0 and actual_date > '2013-12-01'
) X
WHERE row = 65
This will find 2013-12-01 plus 65 workdays, skipping holidays.