Working With Foreign Keys

-- Creating the customers and orders tables

CREATE TABLE customers(
    id INT AUTO_INCREMENT PRIMARY KEY,
    first_name VARCHAR(100),
    last_name VARCHAR(100),
    email VARCHAR(100)
);
CREATE TABLE orders(
    id INT AUTO_INCREMENT PRIMARY KEY,
    order_date DATE,
    amount DECIMAL(8,2),
    customer_id INT,
    FOREIGN KEY(customer_id) REFERENCES customers(id)
);

-- Inserting some customers and orders

INSERT INTO customers (first_name, last_name, email) 
VALUES ('Boy', 'George', 'george@gmail.com'),
       ('George', 'Michael', 'gm@gmail.com'),
       ('David', 'Bowie', 'david@gmail.com'),
       ('Blue', 'Steele', 'blue@gmail.com'),
       ('Bette', 'Davis', 'bette@aol.com');
       
INSERT INTO orders (order_date, amount, customer_id)
VALUES ('2016/02/10', 99.99, 1),
       ('2017/11/11', 35.50, 1),
       ('2014/12/12', 800.67, 2),
       ('2015/01/03', 12.50, 2),
       ('1999/04/11', 450.25, 5);

       
-- This INSERT fails because of our fk constraint.  No user with id: 98

INSERT INTO orders (order_date, amount, customer_id)
VALUES ('2016/06/06', 33.67, 98);