SQLite select inside of update - sqlite

Question

So there are 2 tables, Transactions with created_at column and Transaction_associations with amount and remaining_balance columns, among others. I need to calculate a running sum(total) on the amount column, sorted by the created_at column, obviously. The only problem is that I need to get the SUM of all transactions that are created before the current transaction that is being calculated. I would've needed a select inside the update query in order to SELECT a current_transactions table in order to get hold of the current created_at date. However I can't. Am I missing something? Are there alternatives to this method?
UPDATE Transaction_associations SET remaining_balance =
(
SELECT SUM (Transaction_associations.amount)
FROM Transactions
JOIN Transaction_associations ON Transactions.id = transaction_id
WHERE created_at <= current_transactions.created_at // here
)
WHERE id IN
(
SELECT id
FROM Transaction_associations
JOIN Transactions ON Transactions.id = transaction_id
WHERE created_at >= '2014-11-24'
)
Edit: Added example.
Transactions Transaction_associations
created_at amount remaining_balance
2014-02-01 100 100
2014-03-01 50 150
2014-04-01 205 355
Later Edit: Added complete code for use on SQLFiddle. I've replaced Transaction_associations with TA2 on SUM, as it complains of misuse of aggregate: SUM()
DROP TABLE IF EXISTS Transactions;
DROP TABLE IF EXISTS Transaction_associations;
CREATE TABLE Transactions ( id integer, created_at text);
CREATE TABLE Transaction_associations ( id integer, amount integer, remaining_balance integer, transaction_id integer);
INSERT INTO Transactions VALUES (1,'2015');
INSERT INTO Transactions VALUES (2,'2014');
INSERT INTO Transactions VALUES (3,'2013');
INSERT INTO Transactions VALUES (4,'2012');
INSERT INTO Transactions VALUES (5,'2010');
INSERT INTO Transaction_associations VALUES (6, 100, 0, 1);
INSERT INTO Transaction_associations VALUES (7, 20, 0, 2);
INSERT INTO Transaction_associations VALUES (8, 3, 0, 3);
INSERT INTO Transaction_associations VALUES (9, 40, 0, 4);
INSERT INTO Transaction_associations VALUES (10, 500, 0, 5);
UPDATE Transaction_associations
SET remaining_balance =
(
SELECT SUM(TA2.amount)
FROM Transactions
JOIN Transaction_associations AS TA2 ON Transactions.id = TA2.transaction_id
WHERE created_at <= (SELECT created_at
FROM Transactions
WHERE id = TA2.transaction_id)
)
WHERE transaction_id IN
(
SELECT id
FROM Transactions
WHERE created_at >= '2013'
);
SELECT * from Transactions join Transaction_associations on Transactions.id = Transaction_associations.transaction_id;
This results in, which is wrong:
1 2015 6 100 663 1
2 2014 7 20 663 2
3 2013 8 3 663 3
4 2012 9 40 0 4
5 2010 10 500 0 5
Result should be:
1 2015 6 100 663 1
2 2014 7 20 563 2
3 2013 8 3 543 3
4 2012 9 40 0 4
5 2010 10 500 0 5

Answer 1

To use the same table name multiple times, rename one of them. This is not possible with UPDATE, so you have to do this in the SELECT.
To look up the corresponding timestamp, use another subquery.
Together with some simplifications, this becomes:
UPDATE Transaction_associations
SET remaining_balance =
(
SELECT SUM(TA2.amount)
FROM Transactions
JOIN Transaction_associations AS TA2 ON Transactions.id = TA2.transaction_id
WHERE created_at <= (SELECT created_at
FROM Transactions
WHERE id = Transaction_associations.transaction_id)
)
WHERE transaction_id IN
(
SELECT id
FROM Transactions
WHERE created_at >= '2014-11-24'
);