🧭 Plan और Database · Lesson 02

Database Design (MySQL Tables)

पहले tables में सोचें

कोई भी PHP या Kotlin लिखने से पहले तय करें कि दुकान को कौन-सा data याद रखना है। App की हर screen देखें और पूछें "यह कहाँ से आता है?":

हर screen बताती है कि कौन-सी tables चाहिए

आसान rule: एक चीज़ = एक table, और जब दो चीज़ें जुड़ी हों तो दूसरी का data copy करने की बजाय उसका id (foreign key) store करें।

14 tables (ER diagram)

Customer side — एक user की हर चीज़:

Customer tables: सब में user_id है

Shop side — catalogue और orders:

Catalogue और order tables (+ admins और banners, यहाँ नहीं दिखाए)

Table	क्या store करती है	कहाँ use होती है
users, user_tokens	customer accounts और login tokens	register, login, हर protected call
categories, products, product_images	catalogue	home, search, product detail
banners	home slider images और उनका link	home
cart_items, wishlist	user क्या खरीदना / save करना चाहता है	cart, wishlist, hearts
addresses	delivery addresses (एक default)	checkout
coupons	discount codes और उनके rules	checkout
orders, order_items	placed orders और उनकी lines	my orders, admin
reviews	stars + comments	product detail
admins	दुकान मालिक के logins	admin panel

Data बचाने वाली keys और rules

Database खुद गलत data मना कर देता है, इसलिए PHP में bug होने पर भी data नहीं टूटता:

PRIMARY KEY id INT AUTO_INCREMENT — हर row को unique number मिलता है।
FOREIGN KEY — cart_items.product_id का products में होना ज़रूरी। ON DELETE CASCADE user delete होने पर उसकी cart rows भी हटा देता है।
UNIQUE — हर user का एक email, हर (user, product) की एक cart row, हर (product, user) का एक review। Cart API इसे INSERT … ON DUPLICATE KEY UPDATE के साथ use करती है।
INDEX — idx_products_category और idx_products_price हज़ारों products होने पर भी filtering तेज़ रखते हैं।

SQL – database मना कर देता है

-- Try to put a product that does not exist into a cart
INSERT INTO cart_items (user_id, product_id, qty) VALUES (1, 999, 1);

-- Try to register the same email twice
INSERT INTO users (name, email, password_hash) VALUES ('X', 'test@karteasy.in', 'x');

ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails (`karteasy`.`cart_items`, CONSTRAINT `fk_cart_product` FOREIGN KEY (`product_id`) REFERENCES `products` (`id`) ON DELETE CASCADE) ERROR 1062 (23000): Duplicate entry 'test@karteasy.in' for key 'email'

Data types चुनना

Data	Type	क्यों
Price, MRP, totals	DECIMAL(10,2)	Paise बिल्कुल सही। FLOAT में 0.1 + 0.2 = 0.30000000000000004 हो जाता है।
Status	ENUM('placed','confirmed','shipped','delivered','cancelled')	सिर्फ यही values allowed।
Flags	TINYINT(1)	is_active, is_default, is_featured के लिए 0 / 1।
Pincode	CHAR(6)	हमेशा ठीक 6 digits और कभी गणित में use नहीं होता, इसलिए text की तरह store।
Phone	VARCHAR(15)	Phone number text है, जोड़ने वाला number नहीं।
Token	CHAR(64)	Hex में SHA-256 hash हमेशा 64 characters का।

Orders address और price copy क्यों करते हैं

अगर customer आज ₹1,899 में watch order करे और admin अगले हफ़्ते price ₹2,199 कर दे, तो पुराना order अब भी ₹1,899 ही दिखाना चाहिए। इसलिए order_items name, image और price की copy रखती है, और orders shipping address की copy। इसे snapshot कहते हैं।

Live data (बदल सकता है)

products.price = अब ₹2,199
addresses row edit या delete
product का नाम बदला

Order snapshot (कभी नहीं बदलता)

order_items.price = ₹1,899
orders.ship_address = पूरा text
order_items.name = पुराना नाम

Bill बनने के बाद कभी नहीं बदलना चाहिए

पूरी database.sql

यह backend/database.sql की बिल्कुल वही file है। पहला हिस्सा tables बनाता है, दूसरा sample data डालता है। Password hashes PHP password_hash() से बने हैं।

SQL – backend/database.sql

-- KartEasy e-commerce database (MySQL 5.7+ / MariaDB 10.3+)
-- Import this file in phpMyAdmin (or: mysql -u user -p karteasy < database.sql)

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

DROP TABLE IF EXISTS reviews, order_items, orders, coupons, addresses, wishlist, cart_items,
  product_images, products, banners, categories, user_tokens, users, admins;

CREATE TABLE users (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(80) NOT NULL,
  email VARCHAR(120) NOT NULL UNIQUE,
  phone VARCHAR(15) DEFAULT NULL,
  password_hash VARCHAR(255) NOT NULL,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE user_tokens (
  id INT AUTO_INCREMENT PRIMARY KEY,
  user_id INT NOT NULL,
  token_hash CHAR(64) NOT NULL UNIQUE,          -- sha256 of the token, never the token itself
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  expires_at DATETIME NOT NULL,
  CONSTRAINT fk_tokens_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE admins (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(80) NOT NULL,
  email VARCHAR(120) NOT NULL UNIQUE,
  password_hash VARCHAR(255) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE categories (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(60) NOT NULL,
  slug VARCHAR(70) NOT NULL UNIQUE,
  image VARCHAR(160) DEFAULT NULL,
  sort_order INT NOT NULL DEFAULT 0,
  is_active TINYINT(1) NOT NULL DEFAULT 1
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE banners (
  id INT AUTO_INCREMENT PRIMARY KEY,
  title VARCHAR(100) NOT NULL,
  subtitle VARCHAR(150) DEFAULT NULL,
  image VARCHAR(160) NOT NULL,
  link_type ENUM('none','category','product') NOT NULL DEFAULT 'none',
  link_id INT DEFAULT NULL,
  sort_order INT NOT NULL DEFAULT 0,
  is_active TINYINT(1) NOT NULL DEFAULT 1
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE products (
  id INT AUTO_INCREMENT PRIMARY KEY,
  category_id INT NOT NULL,
  name VARCHAR(150) NOT NULL,
  slug VARCHAR(170) NOT NULL UNIQUE,
  short_desc VARCHAR(255) DEFAULT NULL,
  description TEXT,
  price DECIMAL(10,2) NOT NULL,
  mrp DECIMAL(10,2) NOT NULL,
  stock INT NOT NULL DEFAULT 0,
  image VARCHAR(160) DEFAULT NULL,
  rating_avg DECIMAL(2,1) NOT NULL DEFAULT 0.0,
  rating_count INT NOT NULL DEFAULT 0,
  is_featured TINYINT(1) NOT NULL DEFAULT 0,
  is_active TINYINT(1) NOT NULL DEFAULT 1,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  KEY idx_products_category (category_id),
  KEY idx_products_price (price),
  CONSTRAINT fk_products_category FOREIGN KEY (category_id) REFERENCES categories(id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE product_images (
  id INT AUTO_INCREMENT PRIMARY KEY,
  product_id INT NOT NULL,
  image VARCHAR(160) NOT NULL,
  sort_order INT NOT NULL DEFAULT 0,
  CONSTRAINT fk_pimages_product FOREIGN KEY (product_id) REFERENCES products(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE cart_items (
  id INT AUTO_INCREMENT PRIMARY KEY,
  user_id INT NOT NULL,
  product_id INT NOT NULL,
  qty INT NOT NULL DEFAULT 1,
  UNIQUE KEY uq_cart (user_id, product_id),
  CONSTRAINT fk_cart_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
  CONSTRAINT fk_cart_product FOREIGN KEY (product_id) REFERENCES products(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE wishlist (
  id INT AUTO_INCREMENT PRIMARY KEY,
  user_id INT NOT NULL,
  product_id INT NOT NULL,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  UNIQUE KEY uq_wishlist (user_id, product_id),
  CONSTRAINT fk_wish_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
  CONSTRAINT fk_wish_product FOREIGN KEY (product_id) REFERENCES products(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE addresses (
  id INT AUTO_INCREMENT PRIMARY KEY,
  user_id INT NOT NULL,
  name VARCHAR(80) NOT NULL,
  phone VARCHAR(15) NOT NULL,
  line1 VARCHAR(150) NOT NULL,
  line2 VARCHAR(150) DEFAULT NULL,
  city VARCHAR(60) NOT NULL,
  state VARCHAR(60) NOT NULL,
  pincode CHAR(6) NOT NULL,
  is_default TINYINT(1) NOT NULL DEFAULT 0,
  CONSTRAINT fk_addr_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE coupons (
  id INT AUTO_INCREMENT PRIMARY KEY,
  code VARCHAR(30) NOT NULL UNIQUE,
  type ENUM('flat','percent') NOT NULL,
  value DECIMAL(10,2) NOT NULL,
  min_order DECIMAL(10,2) NOT NULL DEFAULT 0,
  max_discount DECIMAL(10,2) DEFAULT NULL,
  expires_at DATETIME DEFAULT NULL,
  is_active TINYINT(1) NOT NULL DEFAULT 1
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE orders (
  id INT AUTO_INCREMENT PRIMARY KEY,
  order_no VARCHAR(20) NOT NULL UNIQUE,
  user_id INT NOT NULL,
  ship_name VARCHAR(80) NOT NULL,
  ship_phone VARCHAR(15) NOT NULL,
  ship_address VARCHAR(400) NOT NULL,
  subtotal DECIMAL(10,2) NOT NULL,
  discount DECIMAL(10,2) NOT NULL DEFAULT 0,
  delivery_fee DECIMAL(10,2) NOT NULL DEFAULT 0,
  total DECIMAL(10,2) NOT NULL,
  coupon_code VARCHAR(30) DEFAULT NULL,
  payment_method VARCHAR(20) NOT NULL DEFAULT 'COD',
  status ENUM('placed','confirmed','shipped','delivered','cancelled') NOT NULL DEFAULT 'placed',
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
  KEY idx_orders_user (user_id),
  CONSTRAINT fk_orders_user FOREIGN KEY (user_id) REFERENCES users(id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE order_items (
  id INT AUTO_INCREMENT PRIMARY KEY,
  order_id INT NOT NULL,
  product_id INT NOT NULL,
  name VARCHAR(150) NOT NULL,                  -- copy: the product may change later
  image VARCHAR(160) DEFAULT NULL,
  price DECIMAL(10,2) NOT NULL,
  qty INT NOT NULL,
  CONSTRAINT fk_oitems_order FOREIGN KEY (order_id) REFERENCES orders(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

CREATE TABLE reviews (
  id INT AUTO_INCREMENT PRIMARY KEY,
  product_id INT NOT NULL,
  user_id INT NOT NULL,
  rating TINYINT NOT NULL,
  comment VARCHAR(500) DEFAULT NULL,
  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  UNIQUE KEY uq_review (product_id, user_id),
  CONSTRAINT fk_reviews_product FOREIGN KEY (product_id) REFERENCES products(id) ON DELETE CASCADE,
  CONSTRAINT fk_reviews_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

SET FOREIGN_KEY_CHECKS = 1;

-- ---------------------------------------------------------------- sample data
-- Admin panel login: admin@karteasy.in / Admin@123   (change it after the first login!)
INSERT INTO admins (name, email, password_hash) VALUES
('Admin', 'admin@karteasy.in', '$2y$10$2bFUQcMtv1/RBgjWL9smLeZ2beV1G.W/kmefM88hbcDErx1P.w6au');

-- Demo customer: test@karteasy.in / Test@123
INSERT INTO users (name, email, phone, password_hash) VALUES
('Riya Sharma', 'test@karteasy.in', '9876543210', '$2y$10$uH03CdamJqTh78xX6h8anO2bK5SYInjgY9DUD8F0J54uvIpC.vxje');

INSERT INTO categories (id, name, slug, image, sort_order) VALUES
(1, 'Mobiles', 'mobiles', 'uploads/categories/mobiles.png', 1),
(2, 'Fashion', 'fashion', 'uploads/categories/fashion.png', 2),
(3, 'Electronics', 'electronics', 'uploads/categories/electronics.png', 3),
(4, 'Home & Kitchen', 'home-kitchen', 'uploads/categories/home-kitchen.png', 4),
(5, 'Books', 'books', 'uploads/categories/books.png', 5),
(6, 'Sports', 'sports', 'uploads/categories/sports.png', 6);

INSERT INTO products (id, category_id, name, slug, short_desc, description, price, mrp, stock, image, rating_avg, rating_count, is_featured) VALUES
(1, 1, 'Nova 5G Smartphone (8GB/128GB)', 'nova-5g-smartphone', '6.6" AMOLED, 50MP camera, 5000 mAh', '6.6 inch 120Hz AMOLED display, 50 MP dual camera, 5000 mAh battery with 33W fast charging and 5G support.', 14999, 18999, 25, 'uploads/products/p1.png', 4.4, 212, 1),
(2, 1, 'Pulse Lite Smartphone (4GB/64GB)', 'pulse-lite-smartphone', 'Big battery budget phone', '6.5 inch HD+ display, 13 MP camera and a 6000 mAh battery that lasts two days.', 7999, 9999, 40, 'uploads/products/p2.png', 4.1, 98, 0),
(3, 1, 'Fast Charger 33W Type-C', 'fast-charger-33w', 'Charge 0–50% in 25 minutes', '33W fast charger with Type-C cable, overheating protection and BIS certification.', 699, 1199, 120, 'uploads/products/p3.png', 4.3, 451, 0),
(4, 2, 'Men Running Sneakers', 'men-running-sneakers', 'Lightweight mesh, sizes 6–11', 'Breathable mesh upper, cushioned sole and anti-slip grip for daily running and walking.', 1299, 2499, 60, 'uploads/products/p4.png', 4.2, 330, 1),
(5, 2, 'Women Cotton Kurta', 'women-cotton-kurta', 'Pure cotton, machine washable', 'Printed straight kurta in soft breathable cotton, perfect for office and festive wear.', 899, 1599, 45, 'uploads/products/p5.png', 4.5, 187, 1),
(6, 2, 'Classic Denim Jacket', 'classic-denim-jacket', 'Unisex, regular fit', 'Stone-washed denim jacket with metal buttons and two chest pockets.', 1599, 2999, 18, 'uploads/products/p6.png', 4.0, 76, 0),
(7, 3, 'Smart Watch Pro', 'smart-watch-pro', 'AMOLED, SpO2, 7-day battery', '1.43 inch AMOLED screen, heart-rate and SpO2 tracking, 100+ sports modes and Bluetooth calling.', 1899, 4999, 35, 'uploads/products/p7.png', 4.5, 128, 1),
(8, 3, 'Wireless Earbuds X2', 'wireless-earbuds-x2', '30 hrs playback, ENC mic', 'Bluetooth 5.3 earbuds with environmental noise cancellation and 30 hours total playback.', 1099, 2999, 80, 'uploads/products/p8.png', 4.2, 640, 1),
(9, 3, 'Bluetooth Speaker Boom', 'bluetooth-speaker-boom', '20W, waterproof IPX7', '20W stereo sound, deep bass, IPX7 waterproof body and 12 hours battery.', 2499, 3999, 22, 'uploads/products/p9.png', 4.4, 205, 0),
(10, 3, 'Power Bank 20000 mAh', 'power-bank-20000', 'Dual USB + Type-C, 22.5W', 'Slim 20000 mAh power bank with 22.5W fast charging and three outputs.', 1499, 2499, 50, 'uploads/products/p10.png', 4.3, 512, 0),
(11, 4, 'Non-Stick Cookware Set (3 pcs)', 'non-stick-cookware-set', 'Induction friendly', 'Kadai, fry pan and tawa with a durable non-stick coating that works on gas and induction.', 1799, 3299, 30, 'uploads/products/p11.png', 4.1, 143, 1),
(12, 4, 'Steel Water Bottle 1L', 'steel-water-bottle', 'Hot 12h / cold 24h', 'Double-wall vacuum insulated stainless steel bottle, leak-proof lid.', 549, 899, 150, 'uploads/products/p12.png', 4.6, 820, 0),
(13, 5, 'Learn Kotlin in 30 Days', 'learn-kotlin-30-days', 'Beginner friendly, Hindi + English', 'Step-by-step Kotlin book with exercises, perfect before starting Android development.', 349, 499, 70, 'uploads/products/p13.png', 4.7, 66, 1),
(14, 5, 'PHP & MySQL Projects', 'php-mysql-projects', '10 real projects', 'Build ten complete PHP and MySQL projects including an e-commerce API and admin panel.', 399, 599, 55, 'uploads/products/p14.png', 4.6, 41, 0),
(15, 6, 'Yoga Mat 6mm', 'yoga-mat-6mm', 'Anti-skid, with carry strap', 'Thick 6 mm TPE yoga mat with anti-skid texture and a free carry strap.', 699, 1299, 65, 'uploads/products/p15.png', 4.3, 377, 0),
(16, 6, 'Cricket Bat English Willow', 'cricket-bat-english-willow', 'Full size, with cover', 'Grade 3 English willow bat with a cane handle and protective cover.', 3499, 4999, 12, 'uploads/products/p16.png', 4.4, 58, 1);

INSERT INTO product_images (product_id, image, sort_order) VALUES
(1, 'uploads/products/p1.png', 1), (1, 'uploads/products/p1b.png', 2),
(7, 'uploads/products/p7.png', 1), (7, 'uploads/products/p7b.png', 2),
(4, 'uploads/products/p4.png', 1), (4, 'uploads/products/p4b.png', 2);

INSERT INTO banners (title, subtitle, image, link_type, link_id, sort_order) VALUES
('Festive Sale', 'Up to 60% off on electronics', 'uploads/banners/b1.png', 'category', 3, 1),
('New Fashion', 'Kurtas, sneakers & more', 'uploads/banners/b2.png', 'category', 2, 2),
('Smart Watch Pro', 'Now at just ₹1,899', 'uploads/banners/b3.png', 'product', 7, 3);

INSERT INTO coupons (code, type, value, min_order, max_discount, expires_at) VALUES
('WELCOME50', 'flat', 50, 499, NULL, '2027-12-31 23:59:59'),
('SAVE10', 'percent', 10, 999, 300, '2027-12-31 23:59:59');

INSERT INTO reviews (product_id, user_id, rating, comment) VALUES
(7, 1, 5, 'Battery easily lasts a week. Great value!'),
(4, 1, 4, 'Comfortable for daily walks.');

Import करें (phpMyAdmin या terminal)

1phpMyAdmin खोलें (XAMPP: http://localhost/phpmyadmin, Hostinger: hPanel → Databases → phpMyAdmin)
2karteasy नाम का database बनाएँ, collation utf8mb4_unicode_ci (Hostinger पर नाम के आगे prefix लगता है जैसे u123_karteasy)
3उसे select करें → Import tab → database.sql चुनें → Go
414 tables दिखनी चाहिए; products → Browse खोलकर 16 products देखें

phpMyAdmin से import

Terminal

# Create the database (utf8mb4 so ₹, Hindi and emoji work)
mysql -u root -p -e "CREATE DATABASE karteasy CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci"

# Import tables + sample data
mysql -u root -p karteasy < database.sql

# Check
mysql -u root -p karteasy -e "SHOW TABLES"

कुछ queries चलाएँ

SQL

-- How many products in each category, and the cheapest one?
SELECT c.name AS category, COUNT(p.id) AS products, MIN(p.price) AS cheapest
FROM categories c
LEFT JOIN products p ON p.category_id = c.id
GROUP BY c.id
ORDER BY c.sort_order;

+----------------+----------+----------+ | category | products | cheapest | +----------------+----------+----------+ | Mobiles | 3 | 699.00 | | Fashion | 3 | 899.00 | | Electronics | 4 | 1099.00 | | Home & Kitchen | 2 | 549.00 | | Books | 2 | 349.00 | | Sports | 2 | 699.00 | +----------------+----------+----------+

SQL

-- Top deals: biggest discount first (this is what the Home "Top deals" row uses)
SELECT id, name, price, mrp, ROUND((mrp - price) * 100 / mrp) AS off_pct
FROM products
ORDER BY off_pct DESC
LIMIT 4;

+----+----------------------+---------+---------+---------+ | id | name | price | mrp | off_pct | +----+----------------------+---------+---------+---------+ | 8 | Wireless Earbuds X2 | 1099.00 | 2999.00 | 63 | | 7 | Smart Watch Pro | 1899.00 | 4999.00 | 62 | | 4 | Men Running Sneakers | 1299.00 | 2499.00 | 48 | | 6 | Classic Denim Jacket | 1599.00 | 2999.00 | 47 | +----+----------------------+---------+---------+---------+

💡 Tip

पहले query phpMyAdmin में लिखें। सही rows मिलें तो उसे PHP में copy करें। इस course का हर API endpoint ऐसे ही लिखा गया है।

आम गलतियाँ

Money के लिए FLOAT → totals में एक paisa का फ़र्क।
Plain passwords save करना → हमेशा password_hash()।
पूरा product cart row में रखना → prices पुराने हो जाते हैं; सिर्फ product_id और qty रखें।
utf8mb4 भूलना → "₹" और Hindi नाम "???" बन जाते हैं।
Orders वाले products delete करना → is_active = 0 use करें।

अक्सर पूछे जाने वाले प्रश्न (FAQ)

Cart सिर्फ phone में क्यों नहीं रखते?

Server वाला cart हर उस device पर चलता है जहाँ से user login करे, और server checkout से पहले stock और price check कर सकता है। App फिर भी तुरंत दिखाती है क्योंकि हर cart API call पूरा updated cart लौटाती है।

InnoDB और utf8mb4 क्यों?

InnoDB foreign keys और transactions support करता है, जो checkout को चाहिए। utf8mb4 हर character store करता है — ₹, Hindi text और emoji भी; पुराना utf8 emoji store नहीं कर पाता।

क्या products को database से delete करना चाहिए?

नहीं। पुराने orders उनसे जुड़े हैं। KartEasy is_active flag use करता है: admin product "hide" करता है तो वह app से गायब हो जाता है, पर order history सही रहती है।

← E-commerce App Tutorial

Database Design (MySQL Tables)

पहले tables में सोचें

14 tables (ER diagram)

Data बचाने वाली keys और rules

Data types चुनना

Orders address और price copy क्यों करते हैं

Live data (बदल सकता है)

Order snapshot (कभी नहीं बदलता)

पूरी database.sql

Import करें (phpMyAdmin या terminal)

कुछ queries चलाएँ

आम गलतियाँ

अक्सर पूछे जाने वाले प्रश्न (FAQ)

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