mysql字段加唯一约束条件

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

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 (%s, %s)", ('user1', 'user1@example.com'))
    conn.commit()
except mysql.connector.IntegrityError as err:
    print(f"Error: {err}")
finally:
    cursor.close()
    conn.close()

ALTER TABLE users DROP INDEX email;

ALTER TABLE users ADD UNIQUE (email);