implement database persistence layer and core restaurant backend logic

database.sql

@@ -1,141 +1,68 @@
 -- Restaurant Database Management System
---
--- Instructions:
--- 1. Create all required tables.
--- 2. Design appropriate PRIMARY KEY and FOREIGN KEY relationships.
--- 3. Add suitable constraints based on the requirements.
--- 4. Insert initial mock data.
--- 5. Insert at least 3 menu items.
--- 6. The script should be executable from start to finish without errors.
-
+-- Workshop 10 - Database Schema & Initial Data
 
+-- پاک کردن جدول‌های قدیمی در صورت وجود (به ترتیب برعکس وابستگی برای جلوگیری از ارور Foreign Key)
+DROP TABLE IF EXISTS order_details CASCADE;
+DROP TABLE IF EXISTS orders CASCADE;
+DROP TABLE IF EXISTS menu_items CASCADE;
+DROP TABLE IF EXISTS users CASCADE;
 
 -- =======================================================
 -- USER TABLE
 -- =======================================================
---
--- Represents customers using the system.
---
--- Required information:
--- - Unique identifier
--- - Username
--- - Password
--- - Email (optional)
---
--- Requirements:
--- - Each user must have a unique identifier.
--- - Usernames must be unique.
--- - Username and password are required.
--- - Passwords should not be stored in plain text.
---
--- CREATE TABLE ...
-
-
+CREATE TABLE users (
+    id SERIAL PRIMARY KEY,
+    username VARCHAR(50) NOT NULL UNIQUE,
+    password_hash VARCHAR(255) NOT NULL, -- ذخیره به صورت هش شده مطابق نیازمندی
+    email VARCHAR(100)
+);
 
 -- =======================================================
 -- MENU ITEM TABLE
 -- =======================================================
---
--- Represents available food and drink items.
---
--- Required information:
--- - Unique identifier
--- - Name
--- - Description (optional)
--- - Price
--- - Category (optional)
---
--- Requirements:
--- - Each menu item must have a unique identifier.
--- - Name is required.
--- - Price must always be positive.
---
--- CREATE TABLE ...
-
-
+CREATE TABLE menu_items (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(100) NOT NULL,
+    description TEXT,
+    price DECIMAL(10, 2) NOT NULL CHECK (price > 0), -- قید مثبت بودن قیمت
+    category VARCHAR(50)
+);
 
 -- =======================================================
 -- ORDER TABLE
 -- =======================================================
---
--- Represents orders placed by customers.
---
--- Required information:
--- - Unique identifier
--- - Reference to customer
--- - Creation date and time
--- - Total price
---
--- Requirements:
--- - Each order must belong to exactly one user.
--- - A user can have multiple orders.
--- - The relationship between User and Order must be implemented.
---
--- Note:
--- Avoid using reserved SQL keywords as table names.
--- Consider using a name such as "orders" or "customer_orders".
---
--- CREATE TABLE ...
-
-
+-- از نام جایگزین orders استفاده شده چون order کلمه کلیدی رزرو شده SQL است.
+CREATE TABLE orders (
+    id SERIAL PRIMARY KEY,
+    user_id INT NOT NULL,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    total_price DECIMAL(10, 2) NOT NULL DEFAULT 0.00,
+    CONSTRAINT fk_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
+);
 
 -- =======================================================
 -- ORDER DETAIL TABLE
 -- =======================================================
---
--- Represents items inside an order.
---
--- Required information:
--- - Unique identifier
--- - Reference to an order
--- - Reference to a menu item
--- - Quantity
--- - Item price at purchase time
---
--- Requirements:
--- - Each detail record must belong to one order.
--- - Each detail record must reference one menu item.
--- - Quantity must always be greater than zero.
--- - Store the item's price at the moment of purchase.
---
--- CREATE TABLE ...
-
-
+CREATE TABLE order_details (
+    id SERIAL PRIMARY KEY,
+    order_id INT NOT NULL,
+    menu_item_id INT NOT NULL,
+    quantity INT NOT NULL CHECK (quantity > 0), -- قید بزرگتر از صفر بودن تعداد
+    unit_price DECIMAL(10, 2) NOT NULL, -- ذخیره قیمت زمان خرید (اگر بعداً قیمت منو عوض شد، فاکتورهای قبلی خراب نشوند)
+    CONSTRAINT fk_order FOREIGN KEY (order_id) REFERENCES orders(id) ON DELETE CASCADE,
+    CONSTRAINT fk_menu_item FOREIGN KEY (menu_item_id) REFERENCES menu_items(id) ON DELETE RESTRICT
+);
 
 -- =======================================================
--- INITIAL MENU DATA
+-- INITIAL MENU DATA (حداقل ۳ آیتم)
 -- =======================================================
---
--- Insert at least 3 food or drink items.
---
--- Example categories:
--- - Pizza
--- - Burger
--- - Pasta
--- - Drink
---
--- INSERT INTO ...
-
-
+INSERT INTO menu_items (name, description, price, category) VALUES
+('Pizza', 'Delicious Pepperoni Pizza with mozzarella cheese', 10.00, 'Food'),
+('Burger', 'Juicy Beef Burger with cheddar cheese and fries', 8.00, 'Food'),
+('Pasta', 'Creamy Alfredo Pasta with grilled chicken', 12.00, 'Food'),
+('Soda', 'Cold refreshing soft drink', 2.00, 'Drink');
 
 -- =======================================================
--- OPTIONAL TEST DATA
+-- VERIFICATION QUERIES (کدهای تایید صحت ساختار)
 -- =======================================================
---
--- You may insert sample users and orders for testing.
--- This section is optional.
---
--- INSERT INTO ...
-
-
-
--- =======================================================
--- VERIFICATION QUERIES
--- =======================================================
---
--- Uncomment these queries to verify your database.
---
--- SELECT * FROM ...;
--- SELECT * FROM ...;
--- SELECT * FROM ...;
--- SELECT * FROM ...;
+SELECT * FROM menu_items;