根据MySQL检查用户名和密码返回空白

import mysql.connector

def check_credentials(username, password):
    try:
        # 连接到MySQL数据库
        conn = mysql.connector.connect(
            host="localhost",
            user="your_username",
            password="your_password",
            database="your_database"
        )
        
        # 创建游标对象
        cursor = conn.cursor()
        
        # 执行查询语句
        query = "SELECT * FROM users WHERE username = %s AND password = %s"
        cursor.execute(query, (username, password))
        
        # 获取查询结果
        result = cursor.fetchone()
        
        # 关闭游标和连接
        cursor.close()
        conn.close()
        
        return result
    
    except mysql.connector.Error as err:
        print(f"Error: {err}")
        return None

# 示例调用
username = "example_user"
password = "example_password"
result = check_credentials(username, password)

if result:
    print("登录成功")
else:
    print("用户名或密码错误")