mysql字段值唯一性

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

INSERT INTO users (username, email) VALUES ('john_doe', 'john@example.com');
INSERT INTO users (username, email) VALUES ('jane_doe', 'jane@example.com');

INSERT INTO users (username, email) VALUES ('john_doe', 'john@example.com'); -- 会报错，因为username和email都是唯一的

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 ('john_doe', 'john@example.com')")
    conn.commit()
except mysql.connector.IntegrityError as err:
    print(f"Error: {err}")
finally:
    cursor.close()
    conn.close()