-- Table 1: Customers
CREATE TABLE Customers (
    customer_id INTEGER PRIMARY KEY AUTOINCREMENT,
    first_name TEXT NOT NULL,
    last_name TEXT NOT NULL,
    email TEXT NOT NULL UNIQUE,
    phone TEXT,
    address TEXT
);

-- Table 2: Sneakers
CREATE TABLE Sneakers (
    sneaker_id INTEGER PRIMARY KEY AUTOINCREMENT,
    sneaker_name TEXT NOT NULL,
    brand TEXT NOT NULL,
    price REAL NOT NULL,
    size TEXT NOT NULL CHECK (size IN ('6', '7', '8', '9', '10', '11', '12')),
    color TEXT NOT NULL
);

-- Table 3: Orders
CREATE TABLE Orders (
    order_id INTEGER PRIMARY KEY AUTOINCREMENT,
    customer_id INTEGER NOT NULL,
    sneaker_id INTEGER NOT NULL,
    quantity INTEGER NOT NULL CHECK (quantity > 0),
    price REAL NOT NULL CHECK (price >= 0),
    order_date DATE DEFAULT (CURRENT_DATE),
    FOREIGN KEY (customer_id) REFERENCES Customers (customer_id),
    FOREIGN KEY (sneaker_id) REFERENCES Sneakers (sneaker_id)
);