CALCDATE
Updated: 07 February 2011
Use CALCDATE to return a datetime value for a specified Year, Month, and Day.
Syntax
SELECT [wctFinancial].[wct].[CALCDATE](
<@Year, int,>
,<@Month, int,>
,<@Day, int,>)
Arguments
@Year
The integer value representing the year. @Year is an expression that returns an int or that can be implicitly converted to int.
@Month
The integer value representing the month. @Month is an expression that returns an int or that can be implicitly converted to int.
@Day
The integer value representing the day of the month. @Day is an expression that returns an int or that can be implicitly converted to int.
Return Type
datetime
Remarks
· CALCDATE is the equivalent of the DATE function in EXCEL, except that it returns a datetime value instead of integer.
· To convert a year, month, and day combination to an integer, consider using the DATEINT function.
· To convert a year, month, and day combination to an integer, consider using the DATEFLOAT function.
Examples
To represent 07-Feb-2011, enter the following SQL.
SELECT wct.CALCDATE(
2011 --@Year
,2 --@Month
,7 --@Day
) as DATE
This produces the following result.
DATE
-----------------------
2011-02-07 00:00:00.000
(1 row(s) affected)
CALCDATE is language independent. The datetime value returned is consistent across different language settings. Look at the following example.
SET LANGUAGE Italian
SELECT wct.CALCDATE(2011,2,7) as [CALCDATE(2011,2,7)]
,cast('02/07/2011' as datetime) as [cast('02/07/2011' as datetime)]
This returns the following result.
CALCDATE(2011,2,7) cast('02/07/2011' as datetime)
----------------------- ------------------------------
2011-02-07 00:00:00.000 2011-07-02 00:00:00.000
(1 row(s) affected)
SET LANGUAGE us_english
SELECT wct.CALCDATE(2011,2,7) as [CALCDATE(2011,2,7)]
,cast('02/07/2011' as datetime) as [cast('02/07/2011' as datetime)]
This returns the following result
CALCDATE(2011,2,7) cast('02/07/2011' as datetime)
----------------------- ------------------------------
2011-02-07 00:00:00.000 2011-02-07 00:00:00.000
(1 row(s) affected)
As you can see,the same date string was passed in both statements, but the datetime value returned was different based upon the language setting for the database. Using CALCDATE avoids that problem.
CALCDATE allows you to perform operation on the date compenents. You can add or subtract integer values to @Year, @Month, @Date, and still be confident of having a valid value returned.
Let’s say you wanted to generate a schedule that showed the first Monday of every month. Here’s one way to do this in SQL.
SELECT DATEADD(d
,(9 - DATEPART(DW,
cast(
cast(mth as varchar) + '/1/' + cast(2011 as varchar)
as datetime
)
)
) % 7
,cast(
cast(mth as varchar) + '/1/' + cast(2011 as varchar)
as datetime
)
) as [First Monday]
FROM (
VALUES
(1),(2),(3),(4),(5),(6),
(7),(8),(9),(10),(11),(12)
) m(mth)
This produces the following result.
First Monday
-----------------------
2011-01-03 00:00:00.000
2011-02-07 00:00:00.000
2011-03-07 00:00:00.000
2011-04-04 00:00:00.000
2011-05-02 00:00:00.000
2011-06-06 00:00:00.000
2011-07-04 00:00:00.000
2011-08-01 00:00:00.000
2011-09-05 00:00:00.000
2011-10-03 00:00:00.000
2011-11-07 00:00:00.000
2011-12-05 00:00:00.000
(12 row(s) affected)
CALCDATE allows you to perform operations on the components of the date rather than on the date value, simplifying the SQL.
SELECT wct.CALCDATE(2011
,mth
,1 +(9 - DATEPART(DW,wct.CALCDATE(2011,mth,1))) % 7
) as [First Monday]
FROM (
VALUES
(1),(2),(3),(4),(5),(6),
(7),(8),(9),(10),(11),(12)
) m(mth)
This produces the following result.
First Monday
-----------------------
2011-01-03 00:00:00.000
2011-02-07 00:00:00.000
2011-03-07 00:00:00.000
2011-04-04 00:00:00.000
2011-05-02 00:00:00.000
2011-06-06 00:00:00.000
2011-07-04 00:00:00.000
2011-08-01 00:00:00.000
2011-09-05 00:00:00.000
2011-10-03 00:00:00.000
2011-11-07 00:00:00.000
2011-12-05 00:00:00.000
(12 row(s) affected)
As a side note, the reason that we used 9 to represent Monday and did not use 2 in this SQL (2 being the numeric representation of Monday), is that the SQL Server modulo function, %, is really a remainder function. The SQL would look more intuitive if we had used the XLeratorDB modulo function (which is the equivalent of the EXCEL MOD function).SELECT wct.CALCDATE(2011
,mth
,1 + wct.Modulo(
(2 - DATEPART(DW,wct.CALCDATE(2011,mth,1)))
,7)
) as [First Monday]
FROM (
VALUES
(1),(2),(3),(4),(5),(6),
(7),(8),(9),(10),(11),(12)
) m(mth)
This produces the following result.
First Monday
-----------------------
2011-01-03 00:00:00.000
2011-02-07 00:00:00.000
2011-03-07 00:00:00.000
2011-04-04 00:00:00.000
2011-05-02 00:00:00.000
2011-06-06 00:00:00.000
2011-07-04 00:00:00.000
2011-08-01 00:00:00.000
2011-09-05 00:00:00.000
2011-10-03 00:00:00.000
2011-11-07 00:00:00.000
2011-12-05 00:00:00.000
(12 row(s) affected)
In this example, we will calculate the date that US Thanksgiving falls on for the years 2011 through 2020. US Thanksgiving falls on the fourth Thursday in November. Therefore, if the first of November is a Thursday, the earliest that Thanksgiving can occur is on the 22nd of November. Thursday is day number 5.
SELECT wct.CALCDATE(yr
,11
,22 + wct.Modulo(
(5 - DATEPART(DW,wct.CALCDATE(yr,11,22)))
,7)
) as [US Thanksgiving]
FROM (
VALUES
(2011),(2012),(2013),(2014),(2015),
(2016),(2017),(2018),(2019),(2020)
) m(yr)
This produces the following result.
US Thanksgiving
-----------------------
2011-11-24 00:00:00.000
2012-11-22 00:00:00.000
2013-11-28 00:00:00.000
2014-11-27 00:00:00.000
2015-11-26 00:00:00.000
2016-11-24 00:00:00.000
2017-11-23 00:00:00.000
2018-11-22 00:00:00.000
2019-11-28 00:00:00.000
2020-11-26 00:00:00.000
(10 row(s) affected)
In this example, we will calculate the day that the Christmas holiday is observed. Christmas is observed on the 25th of December. However, if the Christmas holdiday falls on a weekend, it is observed on the following Monday.
SELECT CASE DATEPART(DW,wct.CALCDATE(yr,12,25))
WHEN 1 THEN wct.CALCDATE(yr,12,26)
WHEN 7 THEN wct.CALCDATE(yr,12,27)
ELSE wct.CALCDATE(yr,12,25)
END as Christmas
FROM (
VALUES
(2011),(2012),(2013),(2014),(2015),
(2016),(2017),(2018),(2019),(2020)
) m(yr)
This produces the following result.
Christmas
-----------------------
2011-12-26 00:00:00.000
2012-12-25 00:00:00.000
2013-12-25 00:00:00.000
2014-12-25 00:00:00.000
2015-12-25 00:00:00.000
2016-12-26 00:00:00.000
2017-12-25 00:00:00.000
2018-12-25 00:00:00.000
2019-12-25 00:00:00.000
2020-12-25 00:00:00.000
(10 row(s) affected)
CALCDATE can simplify date calculations on the datebase. Let’s say that you are a compnay that has a 52-53 week fiscal year, and the year end is defined as the final Saturday in the year end month. You need to calculate the year end date and the number of days in the year.
DECLARE @YEM as int = 8
SELECT yr
,CAST([Last Saturday] as datetime) as [Last Saturday]
,DATEDIFF(d, [Last Saturday PY], [Last Saturday]) as [Days in Year]
FROM(
SELECT yr
,wct.CALCDATE(yr, @YEM,DATEPART(d,wct.CALCDATE(yr, @YEM+1, 1)-7) + wct.Modulo((7 - DATEPART(DW,wct.CALCDATE(yr, @YEM+1, 1)-7)),7)) as [Last Saturday]
,wct.CALCDATE(yr-1, @YEM,DATEPART(d,wct.CALCDATE(yr-1, @YEM+1, 1)-7) + wct.Modulo((7 - DATEPART(DW,wct.CALCDATE(yr-1, @YEM+1, 1)-7)),7)) as [Last Saturday PY]
FROM (
VALUES
(2005),(2006),(2007),(2008),(2009),
(2010),(2011),(2012),(2013),(2014),
(2015),(2016),(2017),(2018),(2019)
) n(yr)
) m
This produces the following result
yr Last Saturday Days in Year
----------- ----------------------- ------------
2005 2005-08-27 00:00:00.000 364
2006 2006-08-26 00:00:00.000 364
2007 2007-08-25 00:00:00.000 364
2008 2008-08-30 00:00:00.000 371
2009 2009-08-29 00:00:00.000 364
2010 2010-08-28 00:00:00.000 364
2011 2011-08-27 00:00:00.000 364
2012 2012-08-25 00:00:00.000 364
2013 2013-08-31 00:00:00.000 371
2014 2014-08-30 00:00:00.000 364
2015 2015-08-29 00:00:00.000 364
2016 2016-08-27 00:00:00.000 364
2017 2017-08-26 00:00:00.000 364
2018 2018-08-25 00:00:00.000 364
2019 2019-08-31 00:00:00.000 371
(15 row(s) affected)
In this example the year end date is the Saturday that falls closest to the last day of the fiscal year end month.
DECLARE @YEM as int = 8
SELECT yr
,CAST(YE as datetime) as [YE Date]
,DATEDIFF(d, PYE, YE) as [Days in Year]
FROM (
SELECT yr
,wct.CALCDATE(yr, @YEM,DATEPART(d,wct.CALCDATE(yr, @YEM+1, 1)-4) + wct.Modulo((7 - DATEPART(DW,wct.CALCDATE(yr, @YEM+1, 1)-4)),7)) as YE
,wct.CALCDATE(yr-1, @YEM,DATEPART(d,wct.CALCDATE(yr-1, @YEM+1, 1)-4) + wct.Modulo((7 - DATEPART(DW,wct.CALCDATE(yr-1, @YEM+1, 1)-4)),7)) as PYE
FROM (
VALUES
(2005),(2006),(2007),(2008),(2009),
(2010),(2011),(2012),(2013),(2014),
(2015),(2016),(2017),(2018),(2019)
) n(yr)
) m
This produces the following result.
yr YE Date Days in Year
----------- ----------------------- ------------
2005 2005-09-03 00:00:00.000 371
2006 2006-09-02 00:00:00.000 364
2007 2007-09-01 00:00:00.000 364
2008 2008-08-30 00:00:00.000 364
2009 2009-08-29 00:00:00.000 364
2010 2010-08-28 00:00:00.000 364
2011 2011-09-03 00:00:00.000 371
2012 2012-09-01 00:00:00.000 364
2013 2013-08-31 00:00:00.000 364
2014 2014-08-30 00:00:00.000 364
2015 2015-08-29 00:00:00.000 364
2016 2016-09-03 00:00:00.000 371
2017 2017-09-02 00:00:00.000 364
2018 2018-09-01 00:00:00.000 364
2019 2019-08-31 00:00:00.000 364
(15 row(s) affected)