SQLSRV Null value will be deleted by Aggregate or Set - php

Question

i trie to execute a Stored Procedure from PHP. My other SP´s are working correctly. But this one will make problems.
Here is my code for calling the SP:
$sqlStmt = "EXEC MOBILE_CSKLIENT_LoadForSync #pCEGERAETNR = ?";
$con = DatabaseManager::GetDatabaseConnection($serial);
$deviceNr = $this->GetDeviceNr($serial, $deviceId);
$res = sqlsrv_query($con, $sqlStmt, array($deviceNr));
if($res == false)
{
die( print_r( sqlsrv_errors(), true));
}
else
{
die( print_r( sqlsrv_errors(), true));
$result = array();
while($zeile = sqlsrv_fetch($res))
{
echo sqlsrv_get_field($res, 0);
}
}
here is my SP:
GO
/****** Object: StoredProcedure [dbo].[MOBILE_CSKLIENT_LoadForSync] Script Date: 25.02.2014 08:36:01 ******/
ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[MOBILE_CSKLIENT_LoadForSync](#pCEGERAETNR FLOAT)
AS
BEGIN
DECLARE #pLASTCHANGE datetime
SET #pLASTCHANGE = (SELECT MAX(LASTCHANGE) FROM CEMITARB WHERE CEGERAETNR = #pCEGERAETNR)
IF #pLASTCHANGE IS NULL
BEGIN
SELECT K.KLIENTNR, K.PROGRAMMNR, K.NAME,
K.VORNAME, K.[STR], K.PLZ, K.ORT , K.TELEFON1, K.TELEFON2, K.GEBDAT, K.GESCHLECHT, K.KEYKLIFR1, K.MAINVERSION
FROM CSKLIENT K
INNER JOIN S1PAT P ON P.KLIENTNR = K.KLIENTNR
INNER JOIN CSKLIZR Z ON Z.KLIENTNR = K.KLIENTNR
WHERE P.AKTIV = 'J'
AND (Z.AUFNAHME IS NULL OR Z.AUFNAHME <= GetDate())
AND (Z.ENTLASSUNG IS NULL OR Z.ENTLASSUNG >= GetDate())
UNION
SELECT K.KLIENTNR, K.PROGRAMMNR, K.NAME,
K.VORNAME, K.[STR], K.PLZ, K.ORT , K.TELEFON1, K.TELEFON2, K.GEBDAT, K.GESCHLECHT, K.KEYKLIFR1, K.MAINVERSION
FROM CSKLIENT K
INNER JOIN H1BEW B ON B.KLIENTNR = K.KLIENTNR
WHERE B.AKTIV = 'J' AND ZIMMER IS NOT NULL AND BEREICH IS NOT NULL
END
ELSE
BEGIN
SELECT K.KLIENTNR, K.PROGRAMMNR, K.NAME,
K.VORNAME, K.[STR], K.PLZ, K.ORT , K.TELEFON1, K.TELEFON2, K.GEBDAT, K.GESCHLECHT, K.KEYKLIFR1, K.MAINVERSION
FROM CSKLIENT K
INNER JOIN S1PAT P ON P.KLIENTNR = K.KLIENTNR
INNER JOIN CSKLIZR Z ON Z.KLIENTNR = K.KLIENTNR
WHERE P.AKTIV = 'J' AND K.LASTCHANGE >= #pLASTCHANGE
AND (Z.AUFNAHME IS NULL OR Z.AUFNAHME <= GetDate())
AND (Z.ENTLASSUNG IS NULL OR Z.ENTLASSUNG >= GetDate())
UNION
SELECT K.KLIENTNR, K.PROGRAMMNR, K.NAME,
K.VORNAME, K.[STR], K.PLZ, K.ORT , K.TELEFON1, K.TELEFON2, K.GEBDAT, K.GESCHLECHT, K.KEYKLIFR1, K.MAINVERSION
FROM CSKLIENT K
INNER JOIN H1BEW B ON B.KLIENTNR = K.KLIENTNR
WHERE B.AKTIV = 'J' AND ZIMMER IS NOT NULL AND BEREICH IS NOT NULL
AND K.LASTCHANGE >= #pLASTCHANGE
END
END
So i now get the Error:
Error: [Microsoft][SQL Server Native Client 10.0][SQL Server]Warnung: Ein NULL-Wert wird durch einen Aggregat- oder sonstigen SET-Vorgang gel\224scht.
Translatet to English:
A Null value will be delete by a aggregat or a set action
My Procedure works fine if i execute it from the SQL Management Studio.
The Procedure should return 222 rows.
I tried to set:
sqlsrv_configure("WarningsReturnAsErrors", 0);
But then nothing was returned from the Procedure.

Answer 1

i found the solution:
the problem was this line in my SP:
SET #pLASTCHANGE = (SELECT MAX(LASTCHANGE) FROM CEMITARB WHERE CEGERAETNR = #pCEGERAETNR)
LastChange can be Null and this was the problem.
So i changed the code to:
IF((SELECT DISTICT LASTCHANGE FROM CEMITARB WHERE CEGERAETNR = #pCEGERAETNR) IS NULL)
BEGIN
SET #pLASTCHANGE = NULL
END
ELSE
BEGIN
SET #pLASTCHANGE = (SELECT MAX(LASTCHANGE) FROM CEMITARB WHERE CEGERAETNR = #pCEGERAETNR)
END
Now my code executes fine. And sqlsrv_query returns the correct items.