mysql包含外键的查询

CREATE TABLE customers (
    id INT PRIMARY KEY,
    name VARCHAR(100)
);

CREATE TABLE orders (
    id INT PRIMARY KEY,
    customer_id INT,
    order_date DATE,
    FOREIGN KEY (customer_id) REFERENCES customers(id)
);

INSERT INTO customers (id, name) VALUES (1, 'Alice'), (2, 'Bob');
INSERT INTO orders (id, customer_id, order_date) VALUES (101, 1, '2023-01-01'), (102, 2, '2023-01-02');

SELECT o.id, o.order_date, c.name AS customer_name
FROM orders o
JOIN customers c ON o.customer_id = c.id
WHERE c.name = 'Alice';

ALTER TABLE orders
DROP FOREIGN KEY fk_customer_id,
ADD CONSTRAINT fk_customer_id FOREIGN KEY (customer_id) REFERENCES customers(id) ON DELETE CASCADE;

CREATE INDEX idx_customer_id ON orders(customer_id);