mysql 设置唯一性

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(50) NOT NULL UNIQUE,
    email VARCHAR(100) NOT NULL UNIQUE
);

CREATE TABLE orders (
    order_id INT AUTO_INCREMENT PRIMARY KEY,
    user_id INT NOT NULL,
    order_number VARCHAR(50) NOT NULL,
    UNIQUE (user_id, order_number)
);

import mysql.connector

try:
    conn = mysql.connector.connect(user='your_user', password='your_password', host='your_host', database='your_database')
    cursor = conn.cursor()
    query = "INSERT INTO users (username, email) VALUES (%s, %s)"
    cursor.execute(query, ('existing_username', 'existing_email'))
    conn.commit()
except mysql.connector.IntegrityError as err:
    print(f"Error: {err}")
finally:
    cursor.close()
    conn.close()

SHOW CREATE TABLE users;