有数据库的python点餐注册登录界面

好的，我可以给你提供一个简单的Python点餐注册登录界面的代码，使用的是SQLite数据库。请先安装sqlite3库。

import sqlite3

# 连接数据库
conn = sqlite3.connect('restaurant.db')
c = conn.cursor()

# 创建用户表
c.execute('''CREATE TABLE IF NOT EXISTS users
             (id INTEGER PRIMARY KEY AUTOINCREMENT,
              username TEXT NOT NULL UNIQUE,
              password TEXT NOT NULL)''')

# 创建菜单表
c.execute('''CREATE TABLE IF NOT EXISTS menu
             (id INTEGER PRIMARY KEY AUTOINCREMENT,
              dish_name TEXT NOT NULL,
              price REAL NOT NULL)''')

# 添加用户
def add_user(username, password):
    c.execute("INSERT INTO users (username, password) VALUES (?, ?)", (username, password))
    conn.commit()

# 获取用户信息
def get_user(username):
    c.execute("SELECT * FROM users WHERE username=?", (username,))
    user = c.fetchone()
    if user:
        return {'id': user[0], 'username': user[1], 'password': user[2]}
    else:
        return None

# 添加菜品
def add_dish(dish_name, price):
    c.execute("INSERT INTO menu (dish_name, price) VALUES (?, ?)", (dish_name, price))
    conn.commit()

# 获取菜单列表
def get_menu():
    c.execute("SELECT * FROM menu")
    menu = c.fetchall()
    return menu

# 关闭数据库连接
def close_db():
    conn.close()

以上是一个简单的数据库操作函数。下面是一个基于PyQt5的点餐注册登录界面的代码：

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QLineEdit, QPushButton, QListWidget, QListWidgetItem, QMessageBox
from db_utils import add_user, get_user, add_dish, get_menu, close_db

class LoginWidget(QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle('点餐系统')
        self.resize(300, 200)

        self.username_label = QLabel('用户名:', self)
        self.username_label.move(50, 50)
        self.username_input = QLineEdit(self)
        self.username_input.move(110, 50)

        self.password_label = QLabel('密码:', self)
        self.password_label.move(50, 80)
        self.password_input = QLineEdit(self)
        self.password_input.move(110, 80)
        self.password_input.setEchoMode(QLineEdit.Password)

        self.login_button = QPushButton('登录', self)
        self.login_button.move(70, 120)
        self.login_button.clicked.connect(self.login)

        self.register_button = QPushButton('注册', self)
        self.register_button.move(160, 120)
        self.register_button.clicked.connect(self.register)

    def login(self):
        username = self.username_input.text()
        password = self.password_input.text()
        user = get_user(username)
        if user and user['password'] == password:
            self.accept()
        else:
            QMessageBox.warning(self, '错误', '用户名或密码错误！')

    def register(self):
        username = self.username_input.text()
        password = self.password_input.text()
        if username and password:
            user = get_user(username)
            if user:
                QMessageBox.warning(self, '错误', '用户名已存在！')
            else:
                add_user(username, password)
                QMessageBox.information(self, '提示', '注册成功！')
        else:
            QMessageBox.warning(self, '错误', '用户名和密码不能为空！')

class OrderWidget(QWidget):
    def __init__(self, username):
        super().__init__()
        self.setWindowTitle('点餐系统')
        self.resize(300, 400)

        self.username = username

        self.menu_label = QLabel('菜单:', self)
        self.menu_label.move(50, 50)

        self.menu_list = QListWidget(self)
        self.menu_list.move(50, 80)
        menu = get_menu()
        for m in menu:
            item = QListWidgetItem(m[1] + '：' + str(m[2]) + '元')
            item.setData(1, m[0])
            self.menu_list.addItem(item)

        self.order_label = QLabel('我的订单:', self)
        self.order_label.move(50, 220)

        self.order_list = QListWidget(self)
        self.order_list.move(50, 250)

        self.add_button = QPushButton('加入订单', self)
        self.add_button.move(50, 350)
        self.add_button.clicked.connect(self.add_order)

        self.submit_button = QPushButton('提交订单', self)
        self.submit_button.move(160, 350)
        self.submit_button.clicked.connect(self.submit_order)

    def add_order(self):
        items = self.menu_list.selectedItems()
        if items:
            item = items[0]
            order_id = item.data(1)
            order_name = item.text()
            self.order_list.addItem(order_name)
            self.order_list.item(self.order_list.count()-1).setData(1, order_id)

    def submit_order(self):
        total_price = 0
        order_ids = []
        for i in range(self.order_list.count()):
            item = self.order_list.item(i)
            total_price += float(item.text().split('：')[1][:-1])
            order_ids.append(item.data(1))
        if order_ids:
            order_ids_str = ','.join(str(id) for id in order_ids)
            QMessageBox.information(self, '提示', '总价：' + str(total_price) + '元\n订单编号：' + order_ids_str)
        else:
            QMessageBox.warning(self, '错误', '请先选择菜品！')

    def closeEvent(self, event):
        close_db()

class RestaurantApp(QApplication):
    def __init__(self, argv):
        super().__init__(argv)
        self.login_widget = LoginWidget()
        self.login_widget.show()
        if self.login_widget.exec_() == self.login_widget.Accepted:
            username = self.login_widget.username_input.text()
            self.order_widget = OrderWidget(username)
            self.order_widget.show()

if __name__ == '__main__':
    app = RestaurantApp(sys.argv)
    sys.exit(app.exec_())

这个界面中，首先打开登录界面，如果输入的用户名和密码正确，则打开点餐界面，点餐界面中展示了菜单列表，可以选择菜品加入订单，并且可以提交订单。