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如何利用MySQL和Python開發一個簡單的在線訂餐系統

隨著互聯網的快速發展，越來越多的人選擇在線訂餐來解決日常的飲食需求。為了滿足用戶的需求，許多公司開發了各式各樣的在線訂餐系統。本文將介紹如何使用MySQL和Python來開發一個簡單的在線訂餐系統，并提供具體的代碼示例。

首先，我們需要創建一個MySQL數據庫來存儲菜單信息、用戶信息以及訂單信息。可以使用以下SQL語句創建相應的表：

CREATE TABLE IF NOT EXISTS `menu` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `name` VARCHAR(100) NOT NULL,
  `price` DECIMAL(10,2) NOT NULL
);
CREATE TABLE IF NOT EXISTS `users` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `username` VARCHAR(100) NOT NULL,
  `password` VARCHAR(100) NOT NULL
);
CREATE TABLE IF NOT EXISTS `orders` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `user_id` INT NOT NULL,
  `menu_id` INT NOT NULL,
  `quantity` INT NOT NULL,
  `date` DATE NOT NULL
);

接下來，我們使用Python和MySQL連接庫來實現數據庫的連接和操作。以下是MySQL連接的代碼示例：

import mysql.connector

# 連接MySQL數據庫
def connect_db():
    conn = mysql.connector.connect(
        host="localhost",
        user="your_username",
        password="your_password",
        database="your_database"
    )
    return conn

# 查詢菜單
def get_menu():
    conn = connect_db()
    cursor = conn.cursor()
    cursor.execute("SELECT * FROM menu")
    menu = cursor.fetchall()
    cursor.close()
    conn.close()
    return menu

# 用戶注冊
def register(username, password):
    conn = connect_db()
    cursor = conn.cursor()
    cursor.execute("INSERT INTO users (username, password) VALUES (%s, %s)", (username, password))
    conn.commit()
    cursor.close()
    conn.close()

# 用戶登錄
def login(username, password):
    conn = connect_db()
    cursor = conn.cursor()
    cursor.execute("SELECT * FROM users WHERE username = %s AND password = %s", (username, password))
    user = cursor.fetchone()
    cursor.close()
    conn.close()
    return user

# 下訂單
def place_order(user_id, menu_id, quantity, date):
    conn = connect_db()
    cursor = conn.cursor()
    cursor.execute("INSERT INTO orders (user_id, menu_id, quantity, date) VALUES (%s, %s, %s, %s)", (user_id, menu_id, quantity, date))
    conn.commit()
    cursor.close()
    conn.close()

現在我們已經可以從數據庫中查詢菜單、實現用戶注冊和登錄以及下訂單了。

為了讓用戶能夠使用在線訂餐系統，我們需要一個簡單的用戶界面。以下是使用Python的Flask庫來實現一個簡單的網頁界面的代碼示例：

from flask import Flask, render_template, request
app = Flask(__name__)

# 用戶界面
@app.route("/")
def index():
    menu = get_menu()
    return render_template("index.html", menu=menu)

# 用戶注冊
@app.route("/register", methods=["GET", "POST"])
def register_page():
    if request.method == "POST":
        username = request.form["username"]
        password = request.form["password"]
        register(username, password)
        return render_template("success.html")
    return render_template("register.html")

# 用戶登錄
@app.route("/login", methods=["GET", "POST"])
def login_page():
    if request.method == "POST":
        username = request.form["username"]
        password = request.form["password"]
        user = login(username, password)
        if user:
            return render_template("success.html")
        else:
            return render_template("login.html", error="Invalid username or password.")
    return render_template("login.html")

# 下訂單
@app.route("/place_order", methods=["POST"])
def place_order_page():
    user_id = request.form["user_id"]
    menu_id = request.form["menu_id"]
    quantity = request.form["quantity"]
    date = request.form["date"]
    place_order(user_id, menu_id, quantity, date)
    return render_template("success.html")

if __name__ == "__main__":
    app.run()

上述代碼創建了一個基于Flask的簡易網頁界面，包括主頁、用戶注冊頁、用戶登錄頁和下訂單頁。

最后，我們需要創建相應的html模板文件來呈現網頁界面。以下是一個簡單的示例：

index.html：

<!DOCTYPE html>
<html>
<head>
    <title>Online Ordering System</title>
</head>
<body>
    {% for item in menu %}
        <h3>{{ item[1] }}</h3>
        <p>Price: {{ item[2] }}</p>
        <form action="/place_order" method="post">
            <input type="hidden" name="user_id" value="1">
            <input type="hidden" name="menu_id" value="{{ item[0] }}">
            <input type="number" name="quantity" min="1" max="10" placeholder="Quantity" required>
            <input type="date" name="date" required>
            <button type="submit">Order</button>
        </form>
        <hr>
    {% endfor %}
</body>
</html>

<!DOCTYPE html>
<html>
<head>
    <title>User Registration</title>
</head>
<body>
    <h2>User Registration</h2>
    <form action="/register" method="post">
        <input type="text" name="username" placeholder="Username" required>
        <input type="password" name="password" placeholder="Password" required>
        <button type="submit">Register</button>
    </form>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
    <title>User Login</title>
</head>
<body>
    <h2>User Login</h2>
    {% if error %}
        <p style="color:red;">{{ error }}</p>
    {% end %}
    <form action="/login" method="post">
        <input type="text" name="username" placeholder="Username" required>
        <input type="password" name="password" placeholder="Password" required>
        <button type="submit">Login</button>
    </form>
</body>
</html>

success.html：

<!DOCTYPE html>
<html>
<head>
    <title>Success</title>
</head>
<body>
    <h2>Success</h2>
    <p>Your order has been placed successfully.</p>
</body>
</html>

以上就是如何利用MySQL和Python開發一個簡單的在線訂餐系統的詳細代碼示例。通過參考該示例，您可以進一步擴展和優化您的在線訂餐系統，以適應實際需求。

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