Restaurant Database Management System

database.sql

@@ -1,141 +1,96 @@
 -- 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.
+-- This script creates the whole schema from scratch and inserts some
+-- initial data. It can be run from start to finish without errors.
+--
+-- Run with:  psql -U postgres -d restaurant_db -f database.sql
 
 
+-- Drop old tables first so the script is re-runnable.
+-- Order matters because of the foreign keys (drop children before parents).
+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 ...
-
+-- Passwords are stored as a hash (never plain text) by the Java app.
+CREATE TABLE users (
+    id       SERIAL       PRIMARY KEY,
+    username VARCHAR(50)  NOT NULL UNIQUE,
+    password VARCHAR(255) NOT NULL,          -- SHA-256 hex hash
+    email    VARCHAR(255)                    -- optional
+);
 
 
 -- =======================================================
 -- 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,                                 -- optional
+    price       NUMERIC(10, 2) NOT NULL CHECK (price > 0),
+    category    VARCHAR(50)                           -- optional
+);
 
 
 -- =======================================================
--- ORDER TABLE
+-- ORDER TABLE  ("order" is a reserved word, so we use "orders")
 -- =======================================================
---
--- 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 ...
-
+-- Each order belongs to exactly one user (One-to-Many: user -> orders).
+CREATE TABLE orders (
+    id          SERIAL         PRIMARY KEY,
+    user_id     INT            NOT NULL REFERENCES users(id),
+    created_at  TIMESTAMP      NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    total_price NUMERIC(10, 2) NOT NULL DEFAULT 0 CHECK (total_price >= 0)
+);
 
 
 -- =======================================================
 -- 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 ...
-
+-- One line inside an order (One-to-Many: order -> order_details).
+-- "price" is the item price at the moment of purchase, so history stays
+-- correct even if the menu price changes later.
+CREATE TABLE order_details (
+    id           SERIAL         PRIMARY KEY,
+    order_id     INT            NOT NULL REFERENCES orders(id) ON DELETE CASCADE,
+    menu_item_id INT            NOT NULL REFERENCES menu_items(id),
+    quantity     INT            NOT NULL CHECK (quantity > 0),
+    price        NUMERIC(10, 2) NOT NULL CHECK (price > 0)
+);
 
 
 -- =======================================================
--- INITIAL MENU DATA
+-- INITIAL MENU DATA (at least 3 items)
 -- =======================================================
---
--- 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
+    ('Margherita Pizza', 'Classic pizza with tomato, mozzarella and basil', 10.00, 'Pizza'),
+    ('Cheeseburger',     'Beef patty with cheddar, lettuce and tomato',     8.00,  'Burger'),
+    ('Pasta Bolognese',  'Spaghetti with rich beef and tomato sauce',       12.00, 'Pasta'),
+    ('Caesar Salad',     'Romaine, croutons, parmesan and Caesar dressing', 6.50,  'Salad'),
+    ('Coca-Cola',        'Chilled 330ml can',                               2.50,  'Drink');
 
 
 -- =======================================================
 -- OPTIONAL TEST DATA
 -- =======================================================
---
--- You may insert sample users and orders for testing.
--- This section is optional.
---
--- INSERT INTO ...
-
+-- Sample user. The password below is the SHA-256 hash of the text "1234"
+-- so you can log in with username "admin" / password "1234" for testing.
+INSERT INTO users (username, password, email) VALUES
+    ('admin', '03ac674216f3e15c761ee1a5e255f067953623c8b388b4459e13f978d7c846f4', 'admin@pizzeria.com');
 
 
 -- =======================================================
--- VERIFICATION QUERIES
+-- VERIFICATION QUERIES (optional, uncomment to check)
 -- =======================================================
---
--- Uncomment these queries to verify your database.
---
--- SELECT * FROM ...;
--- SELECT * FROM ...;
--- SELECT * FROM ...;
--- SELECT * FROM ...;
+-- SELECT * FROM users;
+-- SELECT * FROM menu_items;
+-- SELECT * FROM orders;
+-- SELECT * FROM order_details;