-----------------------1'st query -------------------------------------------
SELECT UNIQUE(i.C_Order_ID) AS C_Order_ID FROM I_Order i
-->463 rows selected
-----------------------2'nd query---------------------------------
SELECT UNIQUE(i2.C_Order_ID) AS C_Order_ID FROM I_Order i2 WHERE i2.I_IsImported = 'E' AND i2.IsActive = 'Y' AND i2.Processed='N' AND  i2.AD_Client_ID = 1000002
-->  94 rows selected
-----------------------3'rd query---------------------------------
SELECT UNIQUE(i.C_Order_ID) AS C_Order_ID FROM I_Order i WHERE  i.C_Order_ID NOT IN
(
SELECT UNIQUE(i2.C_Order_ID) AS C_Order_ID FROM I_Order i2 WHERE i2.I_IsImported = 'E' AND i2.IsActive = 'Y' AND i2.Processed='N' AND  i2.AD_Client_ID = 1000002
)
 ORDER BY i.C_Order_ID
---> 0 rows selected