Question

I have written a query like this. It is working and giving me the result which I wanted.
I have a SELECT query to get CAR_AMOUNT and HOTEL_AMOUNT.
But, I have to repeat the same SELECT query to get the SUM of both. I am not able to use alias name. How can I avoid this?

SELECT B.EMPLOYEE_ID,
       (select SUM(AMOUNT) 
         FROM travel_reimbursements_items
         WHERE type = 'CAR' 
         AND travel_request_no = B.travel_request_no 
        AND STATUS='APPROVED') as CAR_AMOUNT,
       (select SUM(AMOUNT)
        FROM travel_reimbursements_items 
        WHERE type = 'HOTEL' 
        AND travel_request_no = B.travel_request_no 
        AND STATUS='APPROVED') as HOTEL_AMOUNT,
       NVL((select SUM(AMOUNT) 
            FROM travel_reimbursements_items 
            WHERE type = 'CAR' 
            AND travel_request_no = B.travel_request_no 
            AND STATUS='APPROVED'),0)
        +NVL((select SUM(AMOUNT) 
            FROM travel_reimbursements_items
            WHERE type = 'HOTEL' 
            AND travel_request_no = B.travel_request_no 
            AND STATUS='APPROVED'),0) as TOTAL
FROM TRAVEL_REQUEST_ITEM A
     LEFT OUTER JOIN TRAVEL_REQUEST B 
       ON (B.TRAVEL_REQUEST_NO= A.TRAVEL_REQUEST_SR_NO)

Answer 1

This should work in oracle.

SELECT B.EMPLOYEE_ID,
           SUM(CASE WHEN C.type = 'CAR' and C.STATUS='APPROVED' THEN C.AMOUNT ELSE 0 END) as CAR_AMOUNT,
           SUM(CASE WHEN C.type = 'HOTEL' and C.STATUS='APPROVED' THEN C.AMOUNT ELSE 0 END) as HOTEL_AMOUNT,
           SUM(CASE WHEN C.type IN ('CAR', 'HOTEL') and C.STATUS='APPROVED' THEN C.AMOUNT ELSE 0 END) as TOTAL
FROM TRAVEL_REQUEST_ITEM A
    LEFT OUTER JOIN TRAVEL_REQUEST B ON (B.TRAVEL_REQUEST_NO= A.TRAVEL_REQUEST_SR_NO)
    LEFT OUTER JOIN TRAVEL_REIMBURSEMENTS_ITEMS C ON (C.TRAVEL_REQUEST_NO = A.TRAVEL_REQUEST_SR_NO) 
GROUP BY B.EMPLOYEE_ID

Just do a conditional sum based on the item type.