Обработка NULL значения

SELECT RESULT_ChipIN,  RESULT_IN,  RESULT_ChipOUT, RESULT_OUT  FROM 
 
(SELECT chipinDate, ChipinUserID, SUM(tblChipIN.ChipinSUM) AS RESULT_ChipIN 
FROM tblChipIN
GROUP BY chipinDate, ChipinUserID
HAVING chipinDate LIKE '01.04.2010' AND ChipinUserID LIKE '81') AS 1, 
 
(SELECT inDate, inUserID, SUM(tblIN.inSUM) AS RESULT_IN
FROM tblIN
GROUP BY inDate, inUserID
HAVING inDate LIKE '01.04.2010' AND inUserID LIKE '81') AS 2,
 
(SELECT chipoutDate, chipoutUserID, SUM(tblChipOUT.chipoutSUM) AS RESULT_ChipOUT
FROM tblChipOUT
GROUP BY chipoutDate, chipoutUserID
HAVING chipoutDate LIKE '01.04.2010' AND chipoutUserID LIKE '81') AS 3, 
 
(SELECT outDate, outUserID, (SUM(tblOUT.outSUM) AS RESULT_OUT)
FROM tblOUT
GROUP BY outDate, outUserID
HAVING outDate LIKE '01.04.2010' AND outUserID LIKE '81') AS 4

SELECT SUM(ChipinSUM) AS RESULT_ChipIN,  
       SUM(inSUM) AS RESULT_IN, 
       SUM(chipoutSUM) AS RESULT_ChipOUT, 
       SUM(outSUM) AS RESULT_OUT 
FROM 
     (SELECT chipinDate AS Dat, ChipinUserID AS UserId, ChipinSUM, 0 AS inSUM, 0 AS chipoutSUM, 0 AS outSUM
     FROM tblChipIN
     UNION ALL
     SELECT inDate, inUserID, 0, inSUM, 0, 0
     FROM tblIN
     UNION ALL
     SELECT chipoutDate, chipoutUserID, 0, 0, chipoutSUM, 0
     FROM tblChipOUT
     UNION ALL
     SELECT outDate, outUserID, 0, 0, 0, outSUM
     FROM tblChipOUT) AS Q
WHERE Dat = #04/01/2010# AND UserID = 81
GROUP BY Dat, UserID