请用python语言，mysql数据库编写一个能实现记录人员流动，管理人员出入，只有学生和老师能进入学校的门禁系统

好的，以下是一个简单的基于Python和MySQL的门禁系统示例，它记录人员流动、管理人员出入，并只允许学生和老师进入学校。请注意，这只是一个示例，您需要根据您的需求进行修改和扩展。

首先，您需要安装 `mysql-connector-python` 库：

pip install mysql-connector-python

然后，您需要创建一个MySQL数据库，例如 `access_control`，并创建以下三个表格：

CREATE TABLE `users` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `type` enum('student','teacher','staff') NOT NULL,
  PRIMARY KEY (`id`)
);

CREATE TABLE `entries` (
  `id` int NOT NULL AUTO_INCREMENT,
  `user_id` int NOT NULL,
  `entry_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `exit_time` timestamp NULL DEFAULT NULL,
  PRIMARY KEY (`id`),
  CONSTRAINT `fk_user_entry` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`)
);

CREATE TABLE `doors` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
);

这三个表格分别用于存储用户信息、进出门禁记录和门禁门的信息。

接下来，您可以使用以下Python代码来连接MySQL数据库，创建一个新用户，并将其添加到 `users` 表格中：

import mysql.connector

# Connect to the database
cnx = mysql.connector.connect(user='your_username', password='your_password',
                              host='your_hostname',
                              database='access_control')

# Create a new user
user = {
    'name': 'Alice',
    'type': 'student'
}

# Insert the user into the database
cursor = cnx.cursor()
add_user = ("INSERT INTO users "
            "(name, type) "
            "VALUES (%(name)s, %(type)s)")
cursor.execute(add_user, user)
cnx.commit()
cursor.close()
cnx.close()

接下来，您可以使用以下Python代码来记录用户进出门禁：

import mysql.connector
import datetime

# Connect to the database
cnx = mysql.connector.connect(user='your_username', password='your_password',
                              host='your_hostname',
                              database='access_control')

# Get the user ID by name
cursor = cnx.cursor()
query = ("SELECT id, type FROM users WHERE name = %s")
cursor.execute(query, ('Alice',))
user = cursor.fetchone()
if not user:
    print("User not found")
    cursor.close()
    cnx.close()
    exit()

# Get the door ID by name
query = ("SELECT id FROM doors WHERE name = %s")
cursor.execute(query, ('Main Door',))
door = cursor.fetchone()
if not door:
    print("Door not found")
    cursor.close()
    cnx.close()
    exit()

# Check if the user is allowed to enter the door
if user[1] not in ['student', 'teacher']:
    print("User not allowed to enter")
    cursor.close()
    cnx.close()
    exit()

# Check if the user has already entered the door
query = ("SELECT id, entry_time, exit_time FROM entries WHERE user_id = %s AND exit_time IS NULL")
cursor.execute(query, (user[0],))
entry = cursor.fetchone()
if entry:
    # User has already entered, so record the exit time
    query = ("UPDATE entries SET exit_time = %s WHERE id = %s")
    cursor.execute(query, (datetime.datetime.now(), entry[0]))
    cnx.commit()
    print("User exited at", datetime.datetime.now())
else:
    # User has not entered yet, so record the entry time
    query = ("INSERT INTO entries (user_id, door_id, entry_time) "
             "VALUES (%s, %s, %s)")
    cursor.execute(query, (user[0], door[0], datetime.datetime.now()))
    cnx.commit()
    print("User entered at", datetime.datetime.now())

cursor.close()
cnx.close()

以上代码会记录 Alice 进出门禁，并记录进出门禁的时间。如果 Alice 进入了门禁，它会打印 "User entered at [datetime]"；如果 Alice 退出了门禁，它会打印 "User exited at [datetime]"。如果 Alice 不是学生或老师，或者门禁不存在，它会打印相应的错误消息。

请注意，以上代码只是一个简单的示例，您需要进行修改和扩展，以满足您的需求。例如，您可能需要添加更多的门禁门、用户信息和功能。