Paid Orders View

-- Drill 22 — View للطلبات المدفوعة — SQLite 3.x+
CREATE TABLE orders (
  id INTEGER PRIMARY KEY,
  status TEXT NOT NULL,
  total_halalas INTEGER NOT NULL,
  cancelled_at TEXT
);

INSERT INTO orders VALUES
  (1, 'paid', 5000, NULL),
  (2, 'draft', 3000, NULL),
  (3, 'paid', 9000, 'cancelled');

CREATE VIEW paid_orders AS
SELECT id, total_halalas
FROM orders
WHERE status = 'paid'
  AND cancelled_at IS NULL;

SELECT SUM(total_halalas) AS paid_total_halalas
FROM paid_orders;