逾期發票扣除收款及退款後，還欠多少？

CREATE TABLE customers(id TEXT PRIMARY KEY, name TEXT);
CREATE TABLE invoices(id TEXT PRIMARY KEY, customer_id TEXT, amount_cents INTEGER, due_on TEXT, status TEXT);
CREATE TABLE payments(id TEXT PRIMARY KEY, invoice_id TEXT, amount_cents INTEGER, status TEXT);
CREATE TABLE refunds(id TEXT PRIMARY KEY, payment_id TEXT, amount_cents INTEGER, status TEXT);
INSERT INTO customers VALUES ('C1','Acorn'),('C2','Birch');
INSERT INTO invoices VALUES ('I1','C1',100000,'2026-10-01','issued'),('I2','C2',50000,'2026-10-20','issued'),('I3','C9',20000,'2026-10-02','issued'),('I4','C1',30000,'2026-09-01','void');
INSERT INTO payments VALUES ('P1','I1',40000,'settled'),('P2','I1',20000,'settled'),('P3','I2',50000,'settled'),('P4','I3',20000,'failed');
INSERT INTO refunds VALUES ('R1','P1',10000,'completed'),('R2','P1',5000,'pending'),('R3','P3',50000,'completed');

WITH refunded AS (
 SELECT payment_id,SUM(amount_cents) AS cents FROM refunds
 WHERE status='completed' GROUP BY payment_id
), paid AS (
 SELECT p.invoice_id,SUM(p.amount_cents-COALESCE(r.cents,0)) AS cents
 FROM payments p LEFT JOIN refunded r ON r.payment_id=p.id
 WHERE p.status='settled' GROUP BY p.invoice_id
)
SELECT i.id,i.due_on,i.amount_cents-COALESCE(p.cents,0) AS outstanding_cents
FROM invoices i LEFT JOIN paid p ON p.invoice_id=i.id
WHERE i.status='issued' AND i.due_on<'2026-10-10'
 AND i.amount_cents-COALESCE(p.cents,0)>0 ORDER BY i.id;