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Intensively used function in view needs a minimum and maximum from a table

I have a problem (who not?) with a function which i'm using in a view.
This function is a function which calculates a integer value of a
date. For example: '12/31/2004 00:00:00" becomes 20041231. This is
very handy in a datawarehouse and performes superfast. But here is my
problem.

My calendar table is limited by a couple of years. What happens is
that sometimes a value is loaded which is not in the range of the
Calendardate. What we want to do is when a date is loaded is that this
function insert a minimum date when date < minimum date and a maximum
date when date > maximum date.

Yes i know you're thinking : This is datamanipulation and yes this is
true. But now we loose information in our cubes and reports by inner
joining. So if we can use a minimum and a maximum than a user would
say: "This is strange, a lot of values on 1980/1/1!" instead of "I
think that i have not all the data!"

Greetz

Hennie
Jul 23 '05 #1
2 1729
Hi

If you LEFT or RIGHT JOIN to the calendar table you will get a NULL value
for the column, you can then is CASE to determine the value

CREATE FUNCTION ConvertDate (@datevalue datetime)
RETURNS INT
AS
BEGIN
DECLARE @dateint INT
SELECT @dateint = CAST( CASE WHEN A.Date < '20030101' THEN '19800101'
WHEN A.Date > '20051231' THEN '99991231'
ELSE CONVERT(CHAR(4),C.[Year]) + RIGHT('0'+
CONVERT(VARCHAR(2),C.[Month]),2) + RIGHT('0'+ CONVERT(VARCHAR(2),C.[Day]),2)
END AS INT )
FROM ( SELECT @datevalue AS [Date] ) A
LEFT JOIN CALENDAR C ON C.[Date] = A.[Date]
RETURN @dateint
END
GO

John

"Hennie de Nooijer" <hd********@hotmail.com> wrote in message
news:19**************************@posting.google.c om...
I have a problem (who not?) with a function which i'm using in a view.
This function is a function which calculates a integer value of a
date. For example: '12/31/2004 00:00:00" becomes 20041231. This is
very handy in a datawarehouse and performes superfast. But here is my
problem.

My calendar table is limited by a couple of years. What happens is
that sometimes a value is loaded which is not in the range of the
Calendardate. What we want to do is when a date is loaded is that this
function insert a minimum date when date < minimum date and a maximum
date when date > maximum date.

Yes i know you're thinking : This is datamanipulation and yes this is
true. But now we loose information in our cubes and reports by inner
joining. So if we can use a minimum and a maximum than a user would
say: "This is strange, a lot of values on 1980/1/1!" instead of "I
think that i have not all the data!"

Greetz

Hennie

Jul 23 '05 #2
On 30 Dec 2004 02:38:51 -0800, Hennie de Nooijer wrote:
I have a problem (who not?) with a function which i'm using in a view.
This function is a function which calculates a integer value of a
date. For example: '12/31/2004 00:00:00" becomes 20041231. This is
very handy in a datawarehouse and performes superfast. But here is my
problem.

(snip)

Hi Hennie,

Is this conversion all that your function does? If so, you might want to
try the following alternative (using CURRENT_TIMESTAMP as example; replace
it with your date column / parameter):

SELECT CAST(CONVERT(varchar, CURRENT_TIMESTAMP, 112) AS int)

You could put this in the UDF (probably at least as fast as your current
Calenmdar-table based function), or use it inline as a replacement to the
function call (probably even faster).

It should work for all dates from Jan 1st 1753 through Dec 31st 9999.

Best, Hugo
--

(Remove _NO_ and _SPAM_ to get my e-mail address)
Jul 23 '05 #3

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