Using IF in calculation statement

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November 3rd, 2009, 07:00 AM

iand109

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Query - General - Using IF in calculation statement

Hi,
I have a statement that is calculating days that an employee has been working for the company. This is the statement so far:

Code:

(SELECT     SUM(DATEDIFF(dd, EmpStart, EmpEnd)) AS Expr1
                            FROM          dbo.Employment AS Employment_2
                            WHERE      (dbo.STAFF.AppNo = AppNo)
                            GROUP BY AppNo) AS TimeServed

The bit I need help with is the DATEDIFF bit. It calculates OK if there is an end date. But if end date is null, OR end date is > today, it should use today's date for the calculation.
So I tried something like this:

Code:

SUM(DATEDIFF(dd, EmpStart, (IF EmpEnd IS NULL OR EmpEnd > GetDate() THEN GetDate() ELSE EmpEnd)))

But it didn't work - please can anyone help?
Many thanks

November 3rd, 2009, 07:03 AM

sync_or_swim

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Hi,

This is not tested but you should be able to use ISNull to substitute the current date if the enddate is null:

Code:

SELECT     SUM(DATEDIFF(dd, EmpStart, ISNULL(EmpEnd, getDate()))) AS Expr1
                            FROM          dbo.Employment AS Employment_2
                            WHERE      (dbo.STAFF.AppNo = AppNo)
                            GROUP BY AppNo) AS TimeServed

November 3rd, 2009, 07:23 AM

iand109

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Quote:

Originally Posted by sync_or_swim

This is not tested but you should be able to use ISNull to substitute the current date if the enddate is null:

Code:

SELECT     SUM(DATEDIFF(dd, EmpStart, ISNULL(EmpEnd, getDate()))) AS Expr1
                            FROM          dbo.Employment AS Employment_2
                            WHERE      (dbo.STAFF.AppNo = AppNo)
                            GROUP BY AppNo) AS TimeServed

Yes that did work, you're right. But I also need a bit of conditional code which says that if EmpEnd > Today, then use today's date; sometimes people have given notice, which creates an end date in the future. How could I include that?
Many thanks indeed

November 3rd, 2009, 07:38 AM

sync_or_swim

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You should be able to encorporate a case statement, not tested:

Code:

SELECT     SUM(DATEDIFF(dd, EmpStart, (CASE WHEN DATEDIFF(day, getDate(), EmpEnd) >0 THEN
getDate() WHEN EmpEnd IS NULL THEN getDate() ELSE EmpEnd END)  )) AS Expr1
                            FROM          dbo.Employment AS Employment_2
                            WHERE      (dbo.STAFF.AppNo = AppNo)
                            GROUP BY AppNo) AS TimeServed

November 3rd, 2009, 07:48 AM

iand109

Registered User

Join Date: Aug 2009

Posts: 16

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Quote:

Originally Posted by sync_or_swim

You should be able to encorporate a case statement, not tested:

Code:

SELECT     SUM(DATEDIFF(dd, EmpStart, (CASE WHEN DATEDIFF(day, getDate(), EmpEnd) >0 THEN
getDate() WHEN EmpEnd IS NULL THEN getDate() ELSE EmpEnd END)  )) AS Expr1
                            FROM          dbo.Employment AS Employment_2
                            WHERE      (dbo.STAFF.AppNo = AppNo)
                            GROUP BY AppNo) AS TimeServed

Oh yes yes, it works, you're a total star. I did try a case statement but got it totally wrong. Many thanks indeed!

November 3rd, 2009, 08:00 AM

sync_or_swim

Moderator

Join Date: Mar 2006

Location: South Wales

Posts: 3,461

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Quote:

Originally Posted by iand109

Oh yes yes, it works, you're a total star. I did try a case statement but got it totally wrong. Many thanks indeed!

You're welcome, I'm glad it helped!!

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