mysql创建表设置唯一索引

CREATE UNIQUE INDEX index_name ON table_name (column1, column2, ...);

ALTER TABLE table_name ADD UNIQUE INDEX index_name (column1, column2, ...);

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

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

ALTER TABLE users ADD UNIQUE INDEX idx_unique_email (email);

import mysql.connector

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