Select from Variable Table Name under Function.

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Select from Variable Table Name under Function.

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edward-837480

Posted Monday, September 08, 2008 4:32 AM

SSC Rookie

Group: General Forum Members
Last Login: Wednesday, April 17, 2013 2:10 AM
Points: 32, Visits: 107

Dear Experts,

I need to write the following Funtion to output the TimeStr from a TimeCard table as follows:
----------------------------------------------------

CREATE FUNCTION _fGetTimeStr (@ICard int, @DayFile char(8))
RETURNS varchar(100)
AS
BEGIN
declare @tHHMI char(5) -- In format of hh:mi eg. 07:30 or 13:45
declare @result varchar(100) -- Expect output result '07:30,13:45'
SET @tHHMI = ''
SET @result = '--'

-- However the @DayFile is a variable in format: _Xyymmdd eg. _X080901 (sep 1 2008)

DECLARE fil CURSOR FOR

SELECT Xtime FROM _X080901
WHERE ICard = @ICard
ORDER by Xtime

-- Alright when writing the exact table name,
-- but get error when _X080901 is replaced by @DayFile

OPEN fil

FETCH NEXT FROM fil INTO @tHHMI

WHILE @@fetch_status = 0
BEGIN
IF @result = '--'
BEGIN
SET @result = @tHHMI
END
ELSE
BEGIN
SET @result = @result +','+ @tHHMI
END

FETCH NEXT FROM fil INTO @tHHMI
END
CLOSE fil
DEALLOCATE fil
return @result
END
---------------------------------------------

Can any expert suggest me how to do ?

Is there any alternate way to achieve my requirement ?

Thanks a lot for your help !

Regards,
Edward

Post #565282

GSquared

Posted Monday, September 08, 2008 8:16 AM

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Group: General Forum Members
Last Login: Monday, May 06, 2013 1:09 PM
Points: 15,439, Visits: 9,569

The only way to have a variable table name would be to use dynamic SQL. You can't use dynamic SQL in a function.

Can you use a proc instead of a function and have the return value changed to an output parameter?

Alternately, you might be able to create a view that selects the required data from all of the tables, and have the function select from the view. If you regularly add tables (which is a really, really bad idea), you could set up a job to alter the view as needed.

A better idea is to change the table structure so that the date is a column instead of part of the table name. That will prevent all kinds of problems.

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Post #565436

edward-837480

Posted Monday, September 08, 2008 8:39 PM

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Group: General Forum Members
Last Login: Wednesday, April 17, 2013 2:10 AM
Points: 32, Visits: 107

Hi Lawerance,

Thank you for your suggestions.

I will try to implement by using the stored procedure.

Regards,
Edward

Post #565877

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