Select date + 3 days, not including weekends and holidays - sql

Question

I've found a number of answers to the problem of doing a date-diff, in SQL, not including weekends and holidays. My problem is that I need to do a date comparison - how many child records are there whose work date is within three days of the parent record's send date?
Most of the date-diff answers involve a calendar table, and I think if I can build a sub-select that returns the date+3, I can work out the rest. But I can't figure out how to return a date+3.
So:
CREATE TABLE calendar
(
thedate DATETIME NOT NULL,
isweekday SMALLINT NULL,
isholiday SMALLINT NULL
);
And:
SELECT thedate AS fromdate, xxx AS todate
FROM calendar
What I want is for todate to be fromdate + 72 hours, not counting weekends and holidays. Doing a COUNT(*) where isweekday and not isholiday is simple enough, but doing a DATEADD() is another matter.
I'm not sure where to start.

Answer 1

EDIT:
Changed to include non-workdays as valid fromDates.
WITH rankedDates AS
(
SELECT
thedate
, ROW_NUMBER()
OVER(
ORDER BY thedate
) dateRank
FROM
calendar c
WHERE
c.isweekday = 1
AND
c.isholiday = 0
)
SELECT
c1.fromdate
, rd2.thedate todate
FROM
(
SELECT
c.thedate fromDate
,
(
SELECT
TOP 1 daterank
FROM
rankedDates rd
WHERE
rd.thedate <= c.thedate
ORDER BY
thedate DESC
) dateRank
FROM
calendar c
) c1
LEFT JOIN
rankedDates rd2
ON
c1.dateRank + 3 = rd2.dateRank
You could put a date rank column on the calendar table to simplify this and avoid the CTE:
CREATE TABLE
calendar
(
TheDate DATETIME PRIMARY KEY
, isweekday BIT NOT NULL
, isHoliday BIT NOT NULL DEFAULT 0
, dateRank INT NOT NULL
);
Then you'd set the daterank column only where it's a non-holiday weekday.

Answer 2

This should do the trick, change the number in the "top" to the number of days you want to include.
declare #date as datetime
set #date = '5/23/13'
select
max(_businessDates.thedate)
from (
select
top 3 _Calendar.thedate
from calendar _Calendar
where _Calendar.isWeekday = 1
and _Calendar.isholiday = 0
and _Calendar.thedate >= #date
order by
_Calendar.thedate
) as _businessDates
For a dynamic version that can go forward or backward a certain number of days try this:
declare #date as datetime
declare #DayOffset as int
set #date = '5/28/13'
set #DayOffset = -3
select
(case when #DayOffset >= 0 then
max(_businessDates.thedate)
else
min(_businessDates.thedate)
end)
from (
select
top (abs(#DayOffset) + (case when #DayOffset >= 0 then 1 else 0 end)) _Calendar.thedate
from calendar _Calendar
where _Calendar.isWeekday = 1
and _Calendar.isholiday = 0
and ( (#DayOffset >= 0 and _Calendar.thedate >= #date)
or (#DayOffset < 0 and _Calendar.thedate < #date) )
order by
cast(_Calendar.thedate as int) * (case when #DayOffset >=0 then 1 else -1 end)
) as _businessDates
You can set #DayOffset to a positive or negative number.

Answer 3

You just need DATEADD, unless I'm not understanding your question.
DATEADD(DAY,3,fromdate)
Edit: I see, not counting weekends or Holidays, will update momentarily.
Update: Well looks like Jason nailed it, but on the off chance you're using SQL2012, here's the simple version:
SELECT todate = thedate
fromdate = LEAD(thedate,3) OVER (ORDER BY thedate)
FROM calendar
WHERE isweekday = 1
AND isHoliday = 0

Answer 4

Try this if you need it as a query with dateAdd:
SELECT
allDates.thedate fromDate
,min(nonWeekendHoliday.thedate) toDate
FROM (
SELECT
thedate
FROM
calendar _calendar
) allDates
LEFT JOIN (
SELECT
thedate
FROM
calendar _calendar
WHERE
_calendar.isweekday = 1
AND
_calendar.isholiday = 0
) nonWeekendHoliday
on dateadd(d,3,allDates.thedate) <= nonWeekendHoliday.thedate
where allDates.thedate between '5/20/13' and '5/31/13'
group by
allDates.thedate