Query subtracting

Question

Hi Friends,
I am using oracle 10g and forms 6i and 10g and reports 10g and 6i with windows 2008 server
I have a query item_a,item_b,item_c and other_item. Each query having different where conditons.
So I am adding all the queries using union.
ie
For Import
Add all import amount of  (item_a + item_b + item_c ) and subtract from the total amount based on import
Sum(Decode(..amount..)) -
(SUM(ITEM_A IMPORT)+SUM(ITEM_B IMPORT)+SUM(ITEM_C IMPORT)) Import
For Export
Add all export amount of  (item_a + item_b + item_c ) and subtract from the total amount based on export code
Sum(Decode(..amount..)) -
(SUM(ITEM_A Export )+SUM(ITEM_B Export)+SUM(ITEM_C Expot)) Export
Query start from here
Select 'ITEM_A' item_name, sales_date,
       Sum(Decode(....amount..)) Import,
       Sum(Decode(....amount )) Export
       from sales_dtls t
       group by sales_date
UNION
Select 'ITEM_B' item_name ,sales_date,
       Sum(Decode(...amount..)) Import,
       Sum(Decode(...amount..)) Export
       from sales_dtls t
       group by sales_date
UNION
Select 'ITEM_C' item_name , sales_date,
       Sum(Decode(...amount..)) Import,
       Sum(Decode(...amount..)) Export
       from sales_dtls t
       where <CONDITION>
       group by sales_date
UNION
Select 'ALL_OTHER_ITEM'  item_name, sales_date,
Sum(Decode(..amount..)) -
(SUM(ITEM_A IMPORT)+SUM(ITEM_B IMPORT)+SUM(ITEM_C IMPORT)) Import
Sum(Decode(..amount..)) -
(SUM(ITEM_A Export )+SUM(ITEM_B Export)+SUM(ITEM_C Expot)) Export
Rgds
Rdk

Answer 1

My out put look like this
                IMPORT AMOUNT      EXPORT AMOUNT
ITEM_A             300                          500
ITEM_B             400                          900
ITEM_C             500                          200
OTHER             600                          500 ----- How to find this value
                       1800                         2100
TOTAL IMPORT - 1800
TOTAL EXPORT - 2100
OTHER IMPORT=TOTAL-(ITEM_A+ITEM_B+ITEM_C)
OTHER EXPORT=TOTAL-(ITEM_A+ITEM_B+ITEM_C)
How to make query to find amount for other_item
ie import = 1800-(300+400+500) = 600
ie export = 2100-(500+900+200) = 500