SQL, keep NULL instead of 0 [closed] - sql

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i have a sql stored procedure that for some strange reason return 0 from a user-define-function even if this return a null value.
And more strange, if i moove only this part of stored procedure to a new query, this return correctly NULL, so i cant reproduce it
incriminated column is Abbattimento and the user function is [FN_Abbattimento_Copertura_Processo], linked in this way:
OUTER APPLY dbo.FN_Abbattimento_Copertura_Processo(Kint_TP006_IdAttivita,#AnnoRiferimento, IdLiv4, SPD.Ktyi_TP001_IdSocieta, Ktyi_TP058_IdSocietaService, tyi_TP058_Copertura, 2) [acp]
instead if i add
(Select * FROM dbo.FN_Abbattimento_Copertura_Processo(...)) AS Abbattimento
i get NULL VALUE, so the problem seem the call to function with apply
this is the entire store procedure:
ALTER PROCEDURE [dbo].EXT_Pian_DettaglioProcessi
#AnnoRiferimento SMALLINT = NULL
, #IdSocieta SMALLINT = NULL
, #IDAreaIncaricata SMALLINT = NULL
, #IDAreaCoinvolta SMALLINT = NULL
, #Ufficiale BIT = 0
, #Virtuali BIT = 0
AS
BEGIN
DECLARE #VirtualiIntero AS TINYINT
SET #VirtualiIntero =
CASE #Virtuali
WHEN 0 THEN 2
ELSE 0
END
--IF #IdSocieta = 0
-- SET #IdSocieta = NULL
--print #Virtuali
SELECT
SA.nvc_TP001_Societa AS Societa
, Kint_TP006_IdAttivita AS IdAttivita
, nvc_TP006_Attivita AS Attivita
, AreaIncaricata
, CONVERT(NVARCHAR(10), DataPianificata.InizioValStatus, 103) AS DataPianificazione
, StatusAttuale.DescrizioneStatus AS StatusAttuale
, CONVERT(NVARCHAR(10), StatusAttuale.InizioValStatus, 103) AS Dal
--, IdLiv2 AS IdProcessoLivello2
, Liv2 AS ProcessoLivello2
, IdLiv4 AS IdProcessoLivello4
, Liv4 AS ProcessoLivello4
, SPD.nvc_TP001_Societa AS SocietaProcesso
, SPS.nvc_TP001_SocietaAbbreviata AS SocietaServiceProcesso
, tyi_TP058_Copertura AS Copertura
, ksin_TP058_Anno AS AnnoInizioCopertura
--, CASE Abbattimento
-- WHEN 0 THEN NULL
-- ELSE Abbattimento
-- END AS Abbattimento
, Abbattimento
, TipoCopertura
, ISNULL(CP.CoperturaOverride, 0) + ISNULL(CP.CoperturaAttConRating, 0) AS CoperturaComplessivaProcesso
FROM
-- faccio una distinct per non avere duplicati per area e perimetro
-- non lo faccio nella select iniziale perchè altrimenti dovrei selezionare anche i campi usati solo per ordinamento
(SELECT DISTINCT
Kint_TP013_IdAttivita
, Ksin_TP013_AnnoRifPian
, Ktyi_TP013_ProgressivoPian
FROM Q_TP013_Pianificazione
WHERE
(ISNULL(#IDAreaIncaricata, #IDAreaCoinvolta) IS NULL
OR
Ksin_TP013_IdArea IN (SELECT idarea FROM dbo.FN_StrutturaAree(ISNULL(#IDAreaIncaricata, #IDAreaCoinvolta)))
)) AS Pian
INNER JOIN dbo.[FN_DettaglioPianificazione](#AnnoRiferimento, #Ufficiale) AS FiltroPianificazione
ON IdAttivita = Kint_TP013_IdAttivita
AND Progressivo = Ktyi_TP013_ProgressivoPian
INNER JOIN Q_TP006_Attivita
ON Kint_TP006_IdAttivita = Kint_TP013_IdAttivita
INNER JOIN TP001_Societa AS SA
ON SA.Ktyi_TP001_IdSocieta = tyi_TP006_IdSocieta
INNER JOIN
(SELECT
nvc_TP003_Area AS AreaIncaricata
, Kint_TP024_IdAttivita
FROM
Q_TP024_LinkAttivitaArea
INNER JOIN TP003_Area
ON Ksin_TP003_IdArea = Ksin_TP024_IdArea
WHERE
tyi_TP024_IdTipoLinkAttivitaArea = 1
AND Ksin_TP024_IdArea = COALESCE(#IDAreaIncaricata, Ksin_TP024_IdArea)
) AS AI
ON Kint_TP024_IdAttivita = Kint_TP006_IdAttivita
INNER JOIN dbo.FN_CoperturaProcessiAttivita(#AnnoRiferimento,0, #VirtualiIntero,0)
ON Kint_TP058_IdAttivita = Kint_TP006_IdAttivita
LEFT OUTER JOIN dbo.[FN_StrutturaProcessi](GETDATE())
ON IdLiv4 = Ksin_TP058_IdProcesso
LEFT OUTER JOIN TP001_Societa SPD
ON SPD.Ktyi_TP001_IdSocieta = Ktyi_TP058_IdSocieta
LEFT OUTER JOIN TP001_Societa SPS
ON SPS.Ktyi_TP001_IdSocieta = Ktyi_TP058_IdSocietaService
OUTER APPLY dbo.FN_DataStatusAttivita(Kint_TP006_IdAttivita,1) AS DataPianificata
OUTER APPLY dbo.FN_Status_Attivita_Periodo(GETDATE(), Kint_TP006_IdAttivita, null, null) AS StatusAttuale
OUTER APPLY dbo.FN_Abbattimento_Copertura_Processo(Kint_TP006_IdAttivita,#AnnoRiferimento, IdLiv4, SPD.Ktyi_TP001_IdSocieta, Ktyi_TP058_IdSocietaService, tyi_TP058_Copertura, 2) [acp]
OUTER APPLY dbo.FN_CoperturaProcesso(IdLiv4, SPD.Ktyi_TP001_IdSocieta, SPS.Ktyi_TP001_IdSocieta, #AnnoRiferimento) AS CP
WHERE
Ksin_TP013_AnnoRifPian = #AnnoRiferimento
--and IdAttivita = 12331
ORDER BY
Societa
, IdAttivita
, Ord1
, Ord2
, Ord3
, Ord4
And this is user-function that calculate Abbattimento:
ALTER FUNCTION [dbo].[FN_Abbattimento_Copertura_Processo]
(
-- Add the parameters for the function here
-- Add the parameters for the function here
#idAttivita int,
#anno smallint = 0,
#idProcesso smallint = 0,
#idSocieta tinyint = 0,
#idSocietaService tinyint = 0,
#copertura tinyint = 0,
#tipoAbbattimento TINYINT = 1 --1 Dalla prima presente, 2 dalla precedente
)
RETURNS TABLE
AS
RETURN
(
SELECT
CASE
WHEN #tipoAbbattimento = 1 THEN
(SELECT TOP 1 (CAST(tyi_TP058_Copertura AS SMALLINT) - #copertura)
FROM dbo.Q_TP058_LinkAttivitaLinkProcessoSocieta
WHERE Kint_TP058_IdAttivita = #idAttivita
AND Ksin_TP058_Anno between #anno-5 and #anno
AND Ksin_TP058_IdProcesso = #idProcesso
AND Ktyi_TP058_IdSocieta = #idSocieta
AND Ktyi_TP058_IdSocietaService = #idSocietaService
ORDER BY Ksin_TP058_Anno)
WHEN #tipoAbbattimento = 2 THEN
(SELECT TOP 1 (CAST(tyi_TP058_Copertura AS SMALLINT) - #copertura)
FROM dbo.Q_TP058_LinkAttivitaLinkProcessoSocieta
WHERE Kint_TP058_IdAttivita = #idAttivita
AND Ksin_TP058_Anno between #anno-5 and #anno-1
AND Ksin_TP058_IdProcesso = #idProcesso
AND Ktyi_TP058_IdSocieta = #idSocieta
AND Ktyi_TP058_IdSocietaService = #idSocietaService
ORDER BY Ksin_TP058_Anno DESC)
END AS Abbattimento
)
as you can see in comment now i have a case to convert back 0 to NULL, but honestly i don't like much this solution.
can you help me in finding the cause?

Answer 1

I've not read your query, but maybe will help for you NULLIFin following:
NULLIF(col,0)
It will return NULL if your column equals to 0