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SQL query - inclue only work days

Posted on 2006-10-26
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Last Modified: 2008-01-09
Hi experts,

I have to create a query that determines the difference in time between two dates and then calculate the average time difference based on a grouping of another field. There is a trick however - the calculation of the difference in time should exclude Saturdays and Sundays. The query as follows:

SELECT t.name, AVG(DATEDIFF(dd,t.dateone,t.datetwo) AS time
FROM db.dbo.table t
GROUP BY t.name

I have no idea how to do the exclusion of  Saturdays and Sundays in the calculation. Any help would be much appreciated.

Thanks!
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Question by:avdvyver
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6 Comments
 

Author Comment

by:avdvyver
ID: 17810844
My apologies - the query as follows:

SELECT t.name, AVG(DATEDIFF(dd,t.dateone,t.datetwo)) AS time
FROM db.dbo.table t
GROUP BY t.name
0
 
LVL 75

Accepted Solution

by:
Aneesh Retnakaran earned 500 total points
ID: 17810880
use this function to get the no of working days b/w 2 dates

CREATE FUNCTION dbo.GetWorkingDays
( @StartDate datetime,
@EndDate datetime )
RETURNS INT
AS
BEGIN
DECLARE @WorkDays int, @FirstPart int
DECLARE @FirstNum int, @TotalDays int
DECLARE @LastNum int, @LastPart int
IF (DATEDIFF(day, @StartDate, @EndDate) < 2)
BEGIN
RETURN ( 0 )
END
SELECT
@TotalDays = DATEDIFF(day, @StartDate, @EndDate) - 1,
@FirstPart = CASE DATENAME(weekday, @StartDate)
WHEN 'Sunday' THEN 6
WHEN 'Monday' THEN 5
WHEN 'Tuesday' THEN 4
WHEN 'Wednesday' THEN 3
WHEN 'Thursday' THEN 2
WHEN 'Friday' THEN 1
WHEN 'Saturday' THEN 0
END,
@FirstNum = CASE DATENAME(weekday, @StartDate)
WHEN 'Sunday' THEN 5
WHEN 'Monday' THEN 4
WHEN 'Tuesday' THEN 3
WHEN 'Wednesday' THEN 2
WHEN 'Thursday' THEN 1
WHEN 'Friday' THEN 0
WHEN 'Saturday' THEN 0
END
IF (@TotalDays < @FirstPart)
BEGIN
SELECT @WorkDays = @TotalDays
END
ELSE
BEGIN
SELECT @WorkDays = (@TotalDays - @FirstPart) / 7
SELECT @LastPart = (@TotalDays - @FirstPart) % 7
SELECT @LastNum = CASE
WHEN (@LastPart <> 0) THEN @LastPart - 1
ELSE 0
END
SELECT @WorkDays = @WorkDays * 5 + @FirstNum + @LastNum
END
RETURN ( @WorkDays )
END
GO

0
 
LVL 92

Expert Comment

by:Patrick Matthews
ID: 17810922
Hi avdvyver,

Aneesh's function will get you there, unless you have to consider "holidays", days that are Mon-Fri but for
one reason or another should not be counted as work days.  Will you need to do this?  If so, then you would
have to maintain a table of such days, and modify Aneesh's function to refer to that table.

Regards,

Patrick
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Author Comment

by:avdvyver
ID: 17810931
Hi Patrick,

Luckly I don't have to cater for holiday during the working week.
0
 

Author Comment

by:avdvyver
ID: 17811016
Hi aneeshattingal,

I don't want to sound stuipd ... but I don't understand where the origional query fits into your answer. I'm sure it works, I just don't know where exactly to fit my query in. :)
0
 
LVL 75

Expert Comment

by:Aneesh Retnakaran
ID: 17811025
SELECT t.name, AVG(dbo.GetWorkingdays(t.dateone,t.datetwo) AS time
FROM db.dbo.table t
GROUP BY t.name
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