--------------
INSERT INTO Bill VALUES ('B0002', '2026-09-30 08:20:00', 2, 40000, 'C9999', 'S0004')
--------------

ERROR 1452 (23000) at line 45: Cannot add or update a child row: a foreign key constraint fails (`p81_demo`.`Bill`, CONSTRAINT `Bill_Customer` FOREIGN KEY (`Customer_id`) REFERENCES `Customer` (`id`) ON UPDATE CASCADE)
--------------
DELETE FROM Customer WHERE id = 'C0001'
--------------

ERROR 1451 (23000) at line 47: Cannot delete or update a parent row: a foreign key constraint fails (`p81_demo`.`Bill`, CONSTRAINT `Bill_Customer` FOREIGN KEY (`Customer_id`) REFERENCES `Customer` (`id`) ON UPDATE CASCADE)
+-------+----------+---------------+---------------------------+------+----------+
| bill  | customer | name          | description               | unit | payment  |
+-------+----------+---------------+---------------------------+------+----------+
| B0001 | C0100    | Nabila Rahman | Wash, dry & fold (per kg) |    5 | 40000.00 |
+-------+----------+---------------+---------------------------+------+----------+
+-------+-------------+
| bill  | Customer_id |
+-------+-------------+
| B0001 | C0100       |
+-------+-------------+
