T-SQL get number of working days between 2 dates - sql

Question

I want to calculate the number of working days between 2 given dates. For example if I want to calculate the working days between 2013-01-10 and 2013-01-15, the result must be 3 working days (I don't take into consideration the last day in that interval and I subtract the Saturdays and Sundays). I have the following code that works for most of the cases, except the one in my example.
SELECT (DATEDIFF(day, '2013-01-10', '2013-01-15'))
- (CASE WHEN DATENAME(weekday, '2013-01-10') = 'Sunday' THEN 1 ELSE 0 END)
- (CASE WHEN DATENAME(weekday, DATEADD(day, -1, '2013-01-15')) = 'Saturday' THEN 1 ELSE 0 END)
How can I accomplish this? Do I have to go through all the days and check them? Or is there an easy way to do this.

Answer 1

Please, please, please use a calendar table. SQL Server doesn't know anything about national holidays, company events, natural disasters, etc. A calendar table is fairly easy to build, takes an extremely small amount of space, and will be in memory if it is referenced enough.
Here is an example that creates a calendar table with 30 years of dates (2000 -> 2029) but requires only 200 KB on disk (136 KB if you use page compression). That is almost guaranteed to be less than the memory grant required to process some CTE or other set at runtime.
CREATE TABLE dbo.Calendar
(
dt DATE PRIMARY KEY, -- use SMALLDATETIME if < SQL Server 2008
IsWorkDay BIT
);
DECLARE #s DATE, #e DATE;
SELECT #s = '2000-01-01' , #e = '2029-12-31';
INSERT dbo.Calendar(dt, IsWorkDay)
SELECT DATEADD(DAY, n-1, '2000-01-01'), 1
FROM
(
SELECT TOP (DATEDIFF(DAY, #s, #e)+1) ROW_NUMBER()
OVER (ORDER BY s1.[object_id])
FROM sys.all_objects AS s1
CROSS JOIN sys.all_objects AS s2
) AS x(n);
SET DATEFIRST 1;
-- weekends
UPDATE dbo.Calendar SET IsWorkDay = 0
WHERE DATEPART(WEEKDAY, dt) IN (6,7);
-- Christmas
UPDATE dbo.Calendar SET IsWorkDay = 0
WHERE MONTH(dt) = 12
AND DAY(dt) = 25
AND IsWorkDay = 1;
-- continue with other holidays, known company events, etc.
Now the query you're after is quite simple to write:
SELECT COUNT(*) FROM dbo.Calendar
WHERE dt >= '20130110'
AND dt < '20130115'
AND IsWorkDay = 1;
More info on calendar tables:
http://web.archive.org/web/20070611150639/http://sqlserver2000.databases.aspfaq.com/why-should-i-consider-using-an-auxiliary-calendar-table.html
More info on generating sets without loops:
http://www.sqlperformance.com/tag/date-ranges
Also beware of little things like relying on the English output of DATENAME. I've seen several applications break because some users had a different language setting, and if you're relying on WEEKDAY be sure you set your DATEFIRST setting appropriately...

Answer 2

For stuff like this i tend to maintain a calendar table that also includes bank holidays etc.
The script i use for this is as follows (Note that i didnt write it # i forget where i found it)
SET DATEFIRST 1
SET NOCOUNT ON
GO
--Create ISO week Function (thanks BOL)
CREATE FUNCTION ISOweek ( #DATE DATETIME )
RETURNS INT
AS
BEGIN
DECLARE #ISOweek INT
SET #ISOweek = DATEPART(wk, #DATE) + 1 - DATEPART(wk, CAST(DATEPART(yy, #DATE) AS CHAR(4)) + '0104')
--Special cases: Jan 1-3 may belong to the previous year
IF ( #ISOweek = 0 )
SET #ISOweek = dbo.ISOweek(CAST(DATEPART(yy, #DATE) - 1 AS CHAR(4)) + '12' + CAST(24 + DATEPART(DAY, #DATE) AS CHAR(2))) + 1
--Special case: Dec 29-31 may belong to the next year
IF ( ( DATEPART(mm, #DATE) = 12 )
AND ( ( DATEPART(dd, #DATE) - DATEPART(dw, #DATE) ) >= 28 )
)
SET #ISOweek = 1
RETURN(#ISOweek)
END
GO
--END ISOweek
--CREATE Easter algorithm function
--Thanks to Rockmoose (http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=45689)
CREATE FUNCTION fnDLA_GetEasterdate ( #year INT )
RETURNS CHAR(8)
AS
BEGIN
-- Easter date algorithm of Delambre
DECLARE #A INT ,
#B INT ,
#C INT ,
#D INT ,
#E INT ,
#F INT ,
#G INT ,
#H INT ,
#I INT ,
#K INT ,
#L INT ,
#M INT ,
#O INT ,
#R INT
SET #A = #YEAR % 19
SET #B = #YEAR / 100
SET #C = #YEAR % 100
SET #D = #B / 4
SET #E = #B % 4
SET #F = ( #B + 8 ) / 25
SET #G = ( #B - #F + 1 ) / 3
SET #H = ( 19 * #A + #B - #D - #G + 15 ) % 30
SET #I = #C / 4
SET #K = #C % 4
SET #L = ( 32 + 2 * #E + 2 * #I - #H - #K ) % 7
SET #M = ( #A + 11 * #H + 22 * #L ) / 451
SET #O = 22 + #H + #L - 7 * #M
IF #O > 31
BEGIN
SET #R = #O - 31 + 400 + #YEAR * 10000
END
ELSE
BEGIN
SET #R = #O + 300 + #YEAR * 10000
END
RETURN #R
END
GO
--END fnDLA_GetEasterdate
--Create the table
CREATE TABLE MyDateTable
(
FullDate DATETIME NOT NULL
CONSTRAINT PK_FullDate PRIMARY KEY CLUSTERED ,
Period INT ,
ISOWeek INT ,
WorkingDay VARCHAR(1) CONSTRAINT DF_MyDateTable_WorkDay DEFAULT 'Y'
)
GO
--End table create
--Populate table with required dates
DECLARE #DateFrom DATETIME ,
#DateTo DATETIME ,
#Period INT
SET #DateFrom = CONVERT(DATETIME, '20000101')
--yyyymmdd (1st Jan 2000) amend as required
SET #DateTo = CONVERT(DATETIME, '20991231')
--yyyymmdd (31st Dec 2099) amend as required
WHILE #DateFrom <= #DateTo
BEGIN
SET #Period = CONVERT(INT, LEFT(CONVERT(VARCHAR(10), #DateFrom, 112), 6))
INSERT MyDateTable
( FullDate ,
Period ,
ISOWeek
)
SELECT #DateFrom ,
#Period ,
dbo.ISOweek(#DateFrom)
SET #DateFrom = DATEADD(dd, +1, #DateFrom)
END
GO
--End population
/* Start of WorkingDays UPDATE */
UPDATE MyDateTable
SET WorkingDay = 'B' --B = Bank Holiday
--------------------------------EASTER---------------------------------------------
WHERE FullDate = DATEADD(dd, -2, CONVERT(DATETIME, dbo.fnDLA_GetEasterdate(DATEPART(yy, FullDate)))) --Good Friday
OR FullDate = DATEADD(dd, +1, CONVERT(DATETIME, dbo.fnDLA_GetEasterdate(DATEPART(yy, FullDate))))
--Easter Monday
GO
UPDATE MyDateTable
SET WorkingDay = 'B'
--------------------------------NEW YEAR-------------------------------------------
WHERE FullDate IN ( SELECT MIN(FullDate)
FROM MyDateTable
WHERE DATEPART(mm, FullDate) = 1
AND DATEPART(dw, FullDate) NOT IN ( 6, 7 )
GROUP BY DATEPART(yy, FullDate) )
---------------------MAY BANK HOLIDAYS(Always Monday)------------------------------
OR FullDate IN ( SELECT MIN(FullDate)
FROM MyDateTable
WHERE DATEPART(mm, FullDate) = 5
AND DATEPART(dw, FullDate) = 1
GROUP BY DATEPART(yy, FullDate) )
OR FullDate IN ( SELECT MAX(FullDate)
FROM MyDateTable
WHERE DATEPART(mm, FullDate) = 5
AND DATEPART(dw, FullDate) = 1
GROUP BY DATEPART(yy, FullDate) )
--------------------AUGUST BANK HOLIDAY(Always Monday)------------------------------
OR FullDate IN ( SELECT MAX(FullDate)
FROM MyDateTable
WHERE DATEPART(mm, FullDate) = 8
AND DATEPART(dw, FullDate) = 1
GROUP BY DATEPART(yy, FullDate) )
--------------------XMAS(Move to next working day if on Sat/Sun)--------------------
OR FullDate IN ( SELECT CASE WHEN DATEPART(dw, FullDate) IN ( 6, 7 ) THEN DATEADD(dd, +2, FullDate)
ELSE FullDate
END
FROM MyDateTable
WHERE DATEPART(mm, FullDate) = 12
AND DATEPART(dd, FullDate) IN ( 25, 26 ) )
GO
---------------------------------------WEEKENDS--------------------------------------
UPDATE MyDateTable
SET WorkingDay = 'N'
WHERE DATEPART(dw, FullDate) IN ( 6, 7 )
GO
/* End of WorkingDays UPDATE */
--SELECT * FROM MyDateTable ORDER BY 1
DROP FUNCTION fnDLA_GetEasterdate
DROP FUNCTION ISOweek
--DROP TABLE MyDateTable
SET NOCOUNT OFF
Once you have created the table, finding the number of working days is easy peasy:
SELECT COUNT(FullDate) AS WorkingDays
FROM dbo.tbl_WorkingDays
WHERE WorkingDay = 'Y'
AND FullDate >= CONVERT(DATETIME, '10/01/2013', 103)
AND FullDate < CONVERT(DATETIME, '15/01/2013', 103)
Note that this script includes UK bank holidays, i'm not sure what region you're in.

Answer 3

Here's a simple function that counts working days not including Saturday and Sunday (when counting holidays isn't necessary):
CREATE FUNCTION dbo.udf_GetBusinessDays (
#START_DATE DATE,
#END_DATE DATE
)
RETURNS INT
WITH EXECUTE AS CALLER
AS
BEGIN
DECLARE #NUMBER_OF_DAYS INT = 0;
DECLARE #DAY_COUNTER INT = 0;
DECLARE #BUSINESS_DAYS INT = 0;
DECLARE #CURRENT_DATE DATE;
DECLARE #DAYNAME NVARCHAR(9)
SET #NUMBER_OF_DAYS = DATEDIFF(DAY, #START_DATE, #END_DATE);
WHILE #DAY_COUNTER <= #NUMBER_OF_DAYS
BEGIN
SET #CURRENT_DATE = DATEADD(DAY, #DAY_COUNTER, #START_DATE)
SET #DAYNAME = DATENAME(WEEKDAY, #CURRENT_DATE)
SET #DAY_COUNTER += 1
IF #DAYNAME = N'Saturday' OR #DAYNAME = N'Sunday'
BEGIN
CONTINUE
END
ELSE
BEGIN
SET #BUSINESS_DAYS += 1
END
END
RETURN #BUSINESS_DAYS
END
GO

Answer 4

This is the method I normally use (When not using a calendar table):
DECLARE #T TABLE (Date1 DATE, Date2 DATE);
INSERT #T VALUES ('20130110', '20130115'), ('20120101', '20130101'), ('20120611', '20120701');
SELECT Date1, Date2, WorkingDays
FROM #T t
CROSS APPLY
( SELECT [WorkingDays] = COUNT(*)
FROM Master..spt_values s
WHERE s.Number BETWEEN 1 AND DATEDIFF(DAY, t.date1, t.Date2)
AND s.[Type] = 'P'
AND DATENAME(WEEKDAY, DATEADD(DAY, s.number, t.Date1)) NOT IN ('Saturday', 'Sunday')
) wd
If like I do you have a table with holidays in you can add this in too:
SELECT Date1, Date2, WorkingDays
FROM #T t
CROSS APPLY
( SELECT [WorkingDays] = COUNT(*)
FROM Master..spt_values s
WHERE s.Number BETWEEN 1 AND DATEDIFF(DAY, t.date1, t.Date2)
AND s.[Type] = 'P'
AND DATENAME(WEEKDAY, DATEADD(DAY, s.number, t.Date1)) NOT IN ('Saturday', 'Sunday')
AND NOT EXISTS
( SELECT 1
FROM HolidayTable ht
WHERE ht.Date = DATEADD(DAY, s.number, t.Date1)
)
) wd
The above will only work if your dates are within 2047 days of each other, if you are likely to be calculating larger date ranges you can use this:
SELECT Date1, Date2, WorkingDays
FROM #T t
CROSS APPLY
( SELECT [WorkingDays] = COUNT(*)
FROM ( SELECT [Number] = ROW_NUMBER() OVER(ORDER BY s.number)
FROM Master..spt_values s
CROSS JOIN Master..spt_values s2
) s
WHERE s.Number BETWEEN 1 AND DATEDIFF(DAY, t.date1, t.Date2)
AND DATENAME(WEEKDAY, DATEADD(DAY, s.number, t.Date1)) NOT IN ('Saturday', 'Sunday')
) wd

Answer 5

I did my code in SQL SERVER 2008 (MS SQL) . It works fine for me. I hope it will help you.
DECLARE #COUNTS int,
#STARTDATE date,
#ENDDATE date
SET #STARTDATE ='01/21/2013' /*Start date in mm/dd/yyy */
SET #ENDDATE ='01/26/2013' /*End date in mm/dd/yyy */
SET #COUNTS=0
WHILE (#STARTDATE<=#ENDDATE)
BEGIN
/*Check for holidays*/
IF ( DATENAME(weekday,#STARTDATE)<>'Saturday' and DATENAME(weekday,#STARTDATE)<>'Sunday')
BEGIN
SET #COUNTS=#COUNTS+1
END
SET #STARTDATE=DATEADD(day,1,#STARTDATE)
END
/* Display the no of working days */
SELECT #COUNTS

Answer 6

By Combining #Aaron Bertrand's answer and the Easter Calculation from #HeavenCore's and adding some code of my own, this code creates a calendar from 2000 to 2049 that includes UK (England) Bank Holidays. Usage and notes as per Aaron's answer:
DECLARE #s DATE, #e DATE;
SELECT #s = '2000-01-01' , #e = '2049-12-31';
-- Insert statements for procedure here
CREATE TABLE dbo.Calendar
(
dt DATE PRIMARY KEY, -- use SMALLDATETIME if < SQL Server 2008
IsWorkDay BIT
);
INSERT dbo.Calendar(dt, IsWorkDay)
SELECT DATEADD(DAY, n-1, '2000-01-01'), 1
FROM
(
SELECT TOP (DATEDIFF(DAY, #s, #e)+1) ROW_NUMBER()
OVER (ORDER BY s1.[object_id])
FROM sys.all_objects AS s1
CROSS JOIN sys.all_objects AS s2
) AS x(n);
SET DATEFIRST 1;
-- weekends
UPDATE dbo.Calendar SET IsWorkDay = 0
WHERE DATEPART(WEEKDAY, dt) IN (6,7);
-- Christmas
UPDATE dbo.Calendar SET IsWorkDay = 0
WHERE IsWorkDay = 1 and MONTH(dt) = 12 and
(DAY(dt) in (25,26) or
(DAY(dt) in (27, 28) and DATEPART(WEEKDAY, dt) IN (1,2)) );
-- New Year
UPDATE dbo.Calendar SET IsWorkDay = 0
WHERE IsWorkDay = 1 and MONTH(dt) = 1 AND
( DAY(dt) = 1 or (DAY(dt) IN (2,3) AND DATEPART(WEEKDAY, dt)=1 ));
-- Easter
UPDATE dbo.Calendar SET IsWorkDay = 0
WHERE dt = DATEADD(dd, -2, CONVERT(DATETIME, dbo.fnDLA_GetEasterdate(DATEPART(yy, dt)))) --Good Friday
OR dt = DATEADD(dd, +1, CONVERT(DATETIME, dbo.fnDLA_GetEasterdate(DATEPART(yy, dt)))) --Easter Monday
-- May Day (first Monday in May)
UPDATE dbo.Calendar SET IsWorkDay = 0
WHERE MONTH(dt) = 5 AND DATEPART(WEEKDAY, dt)=1 and DAY(DT)<8;
-- Spring Bank Holiday (last Monday in May apart from 2022 when moved to include Platinum Jubilee bank holiday)
UPDATE dbo.Calendar SET IsWorkDay = 0
WHERE
(YEAR(dt)=2022 and MONTH(dt) = 6 AND DAY(dt) IN (2,3)) OR
(YEAR(dt)<>2022 and MONTH(dt) = 5 AND DATEPART(WEEKDAY, dt)=1 and DAY(DT)>24);
-- Summer Bank Holiday (last Monday in August)
UPDATE dbo.Calendar SET IsWorkDay = 0
WHERE MONTH(dt) = 8 AND DATEPART(WEEKDAY, dt)=1 and DAY(DT)>24;