Select from Variable Table Name under Function.

  • 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

  • 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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  • Hi Lawerance,

    Thank you for your suggestions.

    I will try to implement by using the stored procedure.

    Regards,

    Edward

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