Recursive Function problem

  • Hi,

    My task is to calculate the previous number of days a patient has stayed in a mental health facility ( I work for a Hospital).

    I think I have come up with a solution however I receive the error:

    Server: Msg 217, Level 16, State 1, Line 2

    Maximum stored procedure, function, trigger, or view nesting level exceeded (limit 32).

    Is there any way to "stop" the recursion when the limit is reached rather then showing an error?

    I will also welcome advice on how perform this type of task correctly.

    Please see attached .txt file containing the queries.

    PS. The queries do need some work.....

    PPS. The solution must work in both 2000 and 2005.

    Thanks you very much for taking the time to assist me!

  • I don't think you need a recursive function for this.

    Please post your table structure and some proper sample data.

    Also post your expected result.


    N 56°04'39.16"
    E 12°55'05.25"

  • Peso (2/5/2009)


    I don't think you need a recursive function for this.

    Please post your table structure and some proper sample data.

    Also post your expected result.

    Seconded

  • Hi,

    Expected Result

    --------------------

    SB_EPISODE_NUMBER, PREVIOUS_DAYS

    12345, null

    12346, 17

    12390, null

    12345, 5

    Not all current psych admissions will have any prior psych admission\stay

    The previous admission may or may not be psych stay

    Only stays within the previous 7 days ( and 7 days prior to the last and so on backwards through time) are counted.

    Please see attached schema and data example.

    Thank you for your time.

  • hi,

    I managed to re-write my function to use a while-loop istead of recursion.

    ALTER FUNCTION GET_PREVIOUS_MENTAL_HEALTH_DAYS

    (

    @EPISODE_NUMBER NUMERIC

    )

    RETURNS INT

    AS

    BEGIN

    DECLARE @TOTAL_PREVIOUS_DAYS AS INT

    DECLARE @PREV_DAYS AS INT

    SET @TOTAL_PREVIOUS_DAYS = 0

    WHILE @TOTAL_PREVIOUS_DAYS <= 60 AND @EPISODE_NUMBER IS NOT NULL

    BEGIN

    SET @PREV_DAYS = 0

    SELECT

    @PREV_DAYS = SUM( DATEDIFF(D, STAY.SB_WARD_STAY_START, STAY.SB_WARD_STAY_END))

    FROM

    dbo.SB_WARD_STAY STAY INNER JOIN

    dbo.SB_WARD WARD ON

    STAY.SB_WARD_ID = WARD.SB_WARD_ID AND

    WARD.SB_PSYCHIATRIC_WARD = 'Y'

    WHERE

    STAY.SB_EPISODE_NUMBER = @EPISODE_NUMBER

    SET @TOTAL_PREVIOUS_DAYS = @TOTAL_PREVIOUS_DAYS + @PREV_DAYS

    SET @EPISODE_NUMBER = DBO.GET_PREVIOUS_MENTAL_HEALTH_STAY( @EPISODE_NUMBER )

    END

    IF @TOTAL_PREVIOUS_DAYS > 60

    SET @TOTAL_PREVIOUS_DAYS = 60

    RETURN @TOTAL_PREVIOUS_DAYS

    END

  • If it works for you, great.

    But you should consider rewriting the code as set-based instead.


    N 56°04'39.16"
    E 12°55'05.25"

  • Hi

    First of all you dont need a recursive function to achive this.

    Try achieveing it using loops. If you still want to go ahead with your current logic then you can use @@NESTLEVEL to see what is the recursion level of the function.

    Thanks

    Vijaya Kadiyala

    http://dotnetvj.blogspot.com

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