Write SQL to validate order totals

The Practice Hub syncs orders to PostgreSQL:

sql

CREATE TABLE orders (id TEXT PRIMARY KEY, customer_id TEXT, total NUMERIC, status TEXT);
CREATE TABLE order_lines (order_id TEXT, product_sku TEXT, quantity INT);

After a checkout API test, you need to prove the database matches the API response.

Your task: write the SQL that validates (1) the order exists, (2) line items match the cart, and (3) total equals the sum of line prices minus discount. What would you do if the API says paid but SQL shows no row?