mysql 组合键唯一

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

INSERT INTO users (username, email) VALUES ('testuser', 'test@example.com')
ON DUPLICATE KEY UPDATE email = 'test@example.com';

import mysql.connector

try:
    conn = mysql.connector.connect(user='user', password='password', host='host', database='database')
    cursor = conn.cursor()
    cursor.execute("INSERT INTO users (username, email) VALUES ('testuser', 'test@example.com')")
    conn.commit()
except mysql.connector.IntegrityError as err:
    print(f"Error: {err}")
finally:
    cursor.close()
    conn.close()