Sum of two sum statements - sql-server-2008

Question

DECLARE #aracct VARCHAR(12)
SET #aracct = '49920813'
DECLARE #item_no VARCHAR(12)
SET #item_no = '2319'
SELECT tran_id, * FROM transactions
WHERE account = #aracct AND item_no = #item_no
/*-----------Use if removing certain items from a check-----------*/
CREATE TABLE itemtable (items VARCHAR(6), account VARCHAR(12))
INSERT INTO itemtable VALUES ('2299', #aracct)
INSERT INTO itemtable VALUES ('2300', #aracct)
--INSERT INTO #itemtable VALUES ('')
DECLARE #tran_id_pmt VARCHAR(6)
SET #tran_id_pmt = '209413'
SELECT I1.result - I2.result AS 'final result'
FROM (SELECT SUM(amt_paid) AS result
FROM transactions
WHERE account = #aracct AND item_no = #item_no) AS I1
JOIN (SELECT SUM(amt_paid) AS result
FROM transactions
WHERE account = #aracct AND item_no = (SELECT items FROM itemtable)) AS I2
ON (I1.account = I2.account)
Trying to get the sum 2 select statements and then sum those 2 statements, but I keep getting an error. Any ideas?

Answer 1

You need include account on your subquery so you can use it on the ON condition
SELECT I1.result - I2.result AS 'final result'
FROM (SELECT account, SUM(amt_paid) AS result
^^^^^^^
FROM transactions
WHERE account = #aracct AND item_no = #item_no
GROUP BY account) AS I1
^^^^^^^^^^^^^^^^
JOIN (SELECT account, SUM(amt_paid) AS result
FROM transactions
WHERE account = #aracct AND item_no = (SELECT items FROM itemtable)
GROUP BY account) AS I2
ON (I1.account = I2.account)
^^^^^^^^
You could also solve it with a conditional aggregation.
SELECT SUM(CASE WHEN item_no = #item_no THEN amt_paid
ELSE 0
END)
-
SUM(CASE WHEN item_no IN (SELECT items FROM itemtable) THEN amt_paid
ELSE 0
END) AS 'final result'
FROM Transactions
WHERE account = #aracct