mysql 添加唯一性索引

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(50),
    email VARCHAR(100) UNIQUE
);

INSERT INTO users (username, email) VALUES ('user1', 'user1@example.com');
INSERT INTO users (username, email) VALUES ('user2', 'user1@example.com'); -- 这将导致错误

import mysql.connector

try:
    conn = mysql.connector.connect(user='your_user', password='your_password', host='your_host', database='your_database')
    cursor = conn.cursor()
    
    insert_query = "INSERT INTO users (username, email) VALUES (%s, %s)"
    data = ('user2', 'user1@example.com')
    
    cursor.execute(insert_query, data)
    conn.commit()
except mysql.connector.IntegrityError as err:
    print(f"Error: {err}")
finally:
    cursor.close()
    conn.close()