Last Day of any Month

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Last Day of any Month

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Jeff Moden SSC Guru Points: 1003870 More actions · Answer 1

sreid08 (9/4/2009)

I have this page bookmarked because I can never remember how to get the last day of the month -- or some other date functions. It is very helpful:

http://blog.sqlauthority.com/2007/08/18/sql-server-find-last-day-of-any-month-current-previous-next/%5B/quote%5D

Please see my previous post 2 posts above. 😉 The method at that site misses a whole second of the day and if you have data with times, it could mean that you miss a whole lot of data. Don't use that method... ever.

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Jeff Moden SSC Guru Points: 1003870 More actions · Answer 2

Steve Thompson (9/3/2009)
However, I have one question. This method is contingent on the ability to cast the value 0 as a datetime = 01/01/1900, and -1 as 12/31/1899. Is this a stable standard (pardon the alliteration)? In other words, is it possible that MS could change something in the way they process dates that would cause this to break?

Sure they could change the standard for date serial numbers... it would cause Excel, SQL Server, and a whole bunch of other MS products to break, though. They probably won't spend the money to change it for any reason because they spent enough to make it work correctly for Y2k and to fix the old bug that made the last day of Feb 1900 the 29th. 1900 wasn't a leap year.

Since SQL Server 2008 follows the same "base date serial number" scheme, I'd bet that you're pretty safe another decade or two. 🙂

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Jeff Moden SSC Guru Points: 1003870 More actions · Answer 3

Folks, don't even think of using a user defined function for this. Although it's convenient and you don't have to teach newbies why it works and they don't have to memorize the code to do it, it's just not worth the performance hit. Using a user defined function for this is a whole lot slower than just learning how to do it with inline code.

Let's prove it... here's my normal million row table. Don't let it scare you. It doesn't take any time at all to build...

--===== Create and populate a 1,000,000 row test table.

-- Column "RowNum" has a range of 1 to 100,000 unique numbers

-- Column "SomeInt" has a range of 1 to 50,000 non-unique numbers

-- Column "SomeLetters2" has a range of "AA" to "ZZ" non-unique 2 character strings

-- Column "SomeMoney has a range of 0.0000 to 99.9999 non-unique numbers

-- Column "SomeDate" has a range of >=01/01/2000 and <01/01/2010 non-unique date/times

-- Column "SomeCSV" contains 'Part01,Part02,Part03,Part04,Part05,Part06,Part07,Part08,Part09,Part10'

-- for all rows.

-- Column "SomeHex12" contains 12 random hex characters (ie, 0-9,A-F)

-- Jeff Moden

SELECT TOP 1000000

SomeID = IDENTITY(INT,1,1),

SomeInt = ABS(CHECKSUM(NEWID()))%50000+1,

SomeLetters2 = CHAR(ABS(CHECKSUM(NEWID()))%26+65)

+ CHAR(ABS(CHECKSUM(NEWID()))%26+65),

SomeCSV = CAST('Part01,Part02,Part03,Part04,Part05,Part06,Part07,Part08,Part09,Part10' AS VARCHAR(80)),

SomeMoney = CAST(ABS(CHECKSUM(NEWID()))%10000 /100.0 AS MONEY),

SomeDate = CAST(RAND(CHECKSUM(NEWID()))*3653.0+36524.0 AS DATETIME),

SomeHex12 = RIGHT(NEWID(),12)

INTO #JBMTest

FROM Master.dbo.SysColumns t1

CROSS JOIN Master.dbo.SysColumns t2

--===== Add a primary key just because

ALTER TABLE #JBMTest

ADD PRIMARY KEY CLUSTERED (SomeID)

... and here's a function made from the efficient method Michael Valentine Jones made for finding the last day of the month...

CREATE FUNCTION dbo.LastDayOfMonth (@AnyDate DATETIME)

RETURNS DATETIME

AS

BEGIN

RETURN DATEADD(mm,DATEDIFF(mm,-1,@AnyDate),-1)

END

... and here's a test where we dump the calculation to a dummy variable to take the display speed out of the picture and some stats code to measure the difference...

SET NOCOUNT ON

DECLARE @Bitbucket DATETIME

PRINT '========== Inline method =========='

SET STATISTICS TIME ON

SELECT @Bitbucket = DATEADD(mm,DATEDIFF(mm,-1,SomeDate),-1)

FROM #JBMTest

SET STATISTICS TIME OFF

PRINT '========== UDF method =========='

SET STATISTICS TIME ON

SELECT @Bitbucket = dbo.LastDayOfMonth(SomeDate)

FROM #JBMTest

SET STATISTICS TIME OFF

Last, but not least, here's the results from my humble desktop...

========== Inline method ==========

SQL Server Execution Times:

CPU time = 1172 ms, elapsed time = 4311 ms.

========== UDF method ==========

SQL Server Execution Times:

CPU time = 80047 ms, elapsed time = 147857 ms.

Heh... try it with TaskMgr running and see what it really does to the CPU and the Kernel. A UDF for this very simple thing to memorize just isn't worth it. 😉

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

Change is inevitable... Change for the better is not.

Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally)

Michael Valentine Jones SSC Guru Points: 64818 More actions · Answer 4

Here is another series of tests showing the difference in performance of inline code vs. scalar UDFs.

Demo Performance Penalty of User Defined Functions

http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=78601

The functions in the following links have the best available methods I could find that work for the maximum possible datetime ranges for finding start of time periods, and the last day of time periods. Most can be converted to be run as inline code.

Finding the Start of Time Periods

One of the most common questions is how to remove the time from a datetime so that you end up with just a date. In other words, change 2006/12/13 02:33:48.347 to 2006/12/13 00:00:00.000. The following links have functions that will find the start of Century, Decade, Year, Quarter, Month, Week, Day, Hour, 30 Minutes, 20 Minutes, 15 Minutes, 10 Minutes , 5 Minutes , x number of Minutes ,Minute , or Second.

Start of Time Period Functions:

http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=64755

Start of Week Function:

http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=47307

Finding the End of Time Periods

Sometimes there is a need to find the last day of a time period. The following links have functions that will find the last day of Century, Decade, Year, Quarter, Month, or Week.

End Date of Time Period Functions:

http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=64759

End of Week Function:

http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=64760

For a collection of other links related to datetime in SQL Server, see this:

Date/Time Info and Script Links

http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=64762

sreid08 SSC Veteran Points: 290 More actions · Answer 5

Jeff Moden (9/4/2009)

sreid08 (9/4/2009)
I have this page bookmarked because I can never remember how to get the last day of the month -- or some other date functions. It is very helpful:
http://blog.sqlauthority.com/2007/08/18/sql-server-find-last-day-of-any-month-current-previous-next/%5B/quote%5D
Please see my previous post 2 posts above. 😉 The method at that site misses a whole second of the day and if you have data with times, it could mean that you miss a whole lot of data. Don't use that method... ever.

Hi Jeff -- thank you very much! I have only one report that I am using this in - and it is used to find the last day of the month 3 months ago. I will go and change the code AND delete that web page from my bookmarks!

Thanks Again!

SReid

dfine Ten Centuries Points: 1251 More actions · Answer 6

Try this !!

SELECT CASE WHEN DAY(DATEADD(D,1,GETDATE()))=1 THEN 'MONTH END' ELSE 'NOT MONTH END' END AS PERIOD

Hope this helps.

[font="Calibri"]Raj[/font]