app/questions/restaurant.json

[
  {
    "id": "q1",
    "title": "List all main course items",
    "difficulty": "Beginner",
    "description": "Retrieve the names and prices of all menu items in the Main Course category.",
    "hint": "Use a WHERE clause to filter by category.",
    "expected_sql": "SELECT name, price FROM menu_items WHERE category = 'Main Course';"
  },
  {
    "id": "q2",
    "title": "Find orders by customer ID 1",
    "difficulty": "Beginner",
    "description": "Show all orders placed by the customer with ID 1.",
    "hint": "Use a WHERE clause to filter by customer_id.",
    "expected_sql": "SELECT order_id, order_date, total_amount FROM orders WHERE customer_id = 1;"
  },
  {
    "id": "q3",
    "title": "List all beverages",
    "difficulty": "Beginner",
    "description": "Retrieve the names and prices of all items in the Beverage category.",
    "hint": "Use a WHERE clause to filter by category.",
    "expected_sql": "SELECT name, price FROM menu_items WHERE category = 'Beverage';"
  },
  {
    "id": "q4",
    "title": "Find orders on June 11, 2023",
    "difficulty": "Beginner",
    "description": "Show all orders placed on June 11, 2023.",
    "hint": "Use a WHERE clause with date comparison.",
    "expected_sql": "SELECT order_id, customer_id, total_amount FROM orders WHERE order_date = '2023-06-11';"
  },
  {
    "id": "q5",
    "title": "List unique customer emails",
    "difficulty": "Beginner",
    "description": "Retrieve all unique customer email addresses.",
    "hint": "Use DISTINCT to avoid duplicate emails.",
    "expected_sql": "SELECT DISTINCT email FROM customers;"
  },
  {
    "id": "q6",
    "title": "Items in order ID 3",
    "difficulty": "Beginner",
    "description": "Show the menu items and quantities for order ID 3.",
    "hint": "Join order_items with menu_items and filter by order_id.",
    "expected_sql": "SELECT m.name, oi.quantity FROM order_items oi JOIN menu_items m ON oi.item_id = m.item_id WHERE oi.order_id = 3;"
  },
  {
    "id": "q7",
    "title": "List customer contact details",
    "difficulty": "Beginner",
    "description": "Show names and contact numbers of all customers.",
    "hint": "Select name and contact from the customers table.",
    "expected_sql": "SELECT name, contact FROM customers;"
  },
  {
    "id": "q8",
    "title": "Find high-priced items",
    "difficulty": "Beginner",
    "description": "Retrieve menu items with a price greater than 150.",
    "hint": "Use a WHERE clause to filter by price.",
    "expected_sql": "SELECT name, price FROM menu_items WHERE price > 150;"
  },
  {
    "id": "q9",
    "title": "List all order items",
    "difficulty": "Beginner",
    "description": "Show all order items with their quantities.",
    "hint": "Select from the order_items table.",
    "expected_sql": "SELECT order_item_id, order_id, item_id, quantity FROM order_items;"
  },
  {
    "id": "q10",
    "title": "Find orders above 300",
    "difficulty": "Beginner",
    "description": "Show orders with a total amount greater than 300.",
    "hint": "Use a WHERE clause to filter by total_amount.",
    "expected_sql": "SELECT order_id, customer_id, total_amount FROM orders WHERE total_amount > 300;"
  },
  {
    "id": "q11",
    "title": "Count orders per customer",
    "difficulty": "Intermediate",
    "description": "Show the number of orders placed by each customer, including those with zero orders.",
    "hint": "Use a LEFT JOIN and GROUP BY customer name.",
    "expected_sql": "SELECT c.name, COUNT(o.order_id) AS order_count FROM customers c LEFT JOIN orders o ON c.customer_id = o.customer_id GROUP BY c.name;"
  },
  {
    "id": "q12",
    "title": "Total items ordered per category",
    "difficulty": "Intermediate",
    "description": "Calculate the total quantity of items ordered for each menu item category.",
    "hint": "Join menu_items and order_items, then GROUP BY category.",
    "expected_sql": "SELECT m.category, SUM(oi.quantity) AS total_quantity FROM menu_items m JOIN order_items oi ON m.item_id = oi.item_id GROUP BY m.category;"
  },
  {
    "id": "q13",
    "title": "Average order amount",
    "difficulty": "Intermediate",
    "description": "Calculate the average total amount of all orders.",
    "hint": "Use AVG on total_amount in the orders table.",
    "expected_sql": "SELECT AVG(total_amount) AS avg_order_amount FROM orders;"
  },
  {
    "id": "q14",
    "title": "Most ordered menu item",
    "difficulty": "Intermediate",
    "description": "Identify the menu item with the highest total quantity ordered.",
    "hint": "Join order_items and menu_items, GROUP BY item name, and use LIMIT.",
    "expected_sql": "SELECT m.name, SUM(oi.quantity) AS total_quantity FROM menu_items m JOIN order_items oi ON m.item_id = oi.item_id GROUP BY m.name ORDER BY total_quantity DESC LIMIT 1;"
  },
  {
    "id": "q15",
    "title": "Customers with multiple orders",
    "difficulty": "Intermediate",
    "description": "Find customers who have placed more than one order.",
    "hint": "Use GROUP BY on customer name and HAVING clause.",
    "expected_sql": "SELECT c.name, COUNT(o.order_id) AS order_count FROM customers c JOIN orders o ON c.customer_id = o.customer_id GROUP BY c.name HAVING COUNT(o.order_id) > 1;"
  },
  {
    "id": "q16",
    "title": "Menu items never ordered",
    "difficulty": "Intermediate",
    "description": "List menu items that have never been ordered.",
    "hint": "Use a LEFT JOIN and check for NULL in the order_items table.",
    "expected_sql": "SELECT m.name FROM menu_items m LEFT JOIN order_items oi ON m.item_id = oi.item_id WHERE oi.order_item_id IS NULL;"
  },
  {
    "id": "q17",
    "title": "Order details with items",
    "difficulty": "Intermediate",
    "description": "Show order details including customer name and menu items for each order.",
    "hint": "Join orders, customers, order_items, and menu_items tables.",
    "expected_sql": "SELECT o.order_id, c.name AS customer_name, m.name AS item_name, oi.quantity FROM orders o JOIN customers c ON o.customer_id = c.customer_id JOIN order_items oi ON o.order_id = oi.order_id JOIN menu_items m ON oi.item_id = m.item_id;"
  },
  {
    "id": "q18",
    "title": "Total revenue per customer",
    "difficulty": "Intermediate",
    "description": "Calculate the total amount spent by each customer based on order totals.",
    "hint": "Use GROUP BY on customer name and SUM on total_amount.",
    "expected_sql": "SELECT c.name, SUM(o.total_amount) AS total_spent FROM customers c JOIN orders o ON c.customer_id = o.customer_id GROUP BY c.name;"
  },
  {
    "id": "q19",
    "title": "Orders with multiple items",
    "difficulty": "Intermediate",
    "description": "List orders that include more than one type of menu item.",
    "hint": "Use GROUP BY on order_id and HAVING clause on COUNT of item_id.",
    "expected_sql": "SELECT o.order_id, COUNT(oi.item_id) AS item_count FROM orders o JOIN order_items oi ON o.order_id = oi.order_id GROUP BY o.order_id HAVING COUNT(oi.item_id) > 1;"
  },
  {
    "id": "q20",
    "title": "Items ordered with high quantity",
    "difficulty": "Intermediate",
    "description": "Show menu items with a total ordered quantity greater than 2.",
    "hint": "Join order_items and menu_items, GROUP BY item name, and use HAVING.",
    "expected_sql": "SELECT m.name, SUM(oi.quantity) AS total_quantity FROM menu_items m JOIN order_items oi ON m.item_id = oi.item_id GROUP BY m.name HAVING SUM(oi.quantity) > 2;"
  },
  {
    "id": "q21",
    "title": "Customer order value analysis",
    "difficulty": "Advanced",
    "description": "Calculate the total value of orders (sum of price * quantity) for each customer.",
    "hint": "Join all tables, multiply price by quantity, and GROUP BY customer name.",
    "expected_sql": "SELECT c.name, SUM(m.price * oi.quantity) AS total_order_value FROM customers c JOIN orders o ON c.customer_id = o.customer_id JOIN order_items oi ON o.order_id = oi.order_id JOIN menu_items m ON oi.item_id = m.item_id GROUP BY c.name;"
  },
  {
    "id": "q22",
    "title": "Most expensive order",
    "difficulty": "Advanced",
    "description": "Identify the order with the highest calculated total based on item prices and quantities.",
    "hint": "Join orders, order_items, and menu_items, calculate total, and use LIMIT.",
    "expected_sql": "SELECT o.order_id, SUM(m.price * oi.quantity) AS calculated_total FROM orders o JOIN order_items oi ON o.order_id = oi.order_id JOIN menu_items m ON oi.item_id = m.item_id GROUP BY o.order_id ORDER BY calculated_total DESC LIMIT 1;"
  },
  {
    "id": "q23",
    "title": "Customers ordering all main courses",
    "difficulty": "Advanced",
    "description": "Find customers who have ordered every item in the Main Course category.",
    "hint": "Count distinct Main Course items per customer and compare with total Main Course items.",
    "expected_sql": "SELECT c.name FROM customers c JOIN orders o ON c.customer_id = o.customer_id JOIN order_items oi ON o.order_id = oi.order_id JOIN menu_items m ON oi.item_id = m.item_id WHERE m.category = 'Main Course' GROUP BY c.name HAVING COUNT(DISTINCT m.item_id) = (SELECT COUNT(*) FROM menu_items WHERE category = 'Main Course');"
  },
  {
    "id": "q24",
    "title": "Average item price per order",
    "difficulty": "Advanced",
    "description": "Calculate the average price of items in each order.",
    "hint": "Join order_items and menu_items, GROUP BY order_id, and use AVG.",
    "expected_sql": "SELECT o.order_id, AVG(m.price) AS avg_item_price FROM orders o JOIN order_items oi ON o.order_id = oi.order_id JOIN menu_items m ON oi.item_id = m.item_id GROUP BY o.order_id;"
  },
  {
    "id": "q25",
    "title": "Order frequency by date",
    "difficulty": "Advanced",
    "description": "Show the number of orders placed on each date in June 2023.",
    "hint": "Use GROUP BY on order_date and COUNT.",
    "expected_sql": "SELECT order_date, COUNT(order_id) AS order_count FROM orders WHERE order_date LIKE '2023-06%' GROUP BY order_date;"
  },
  {
    "id": "q26",
    "title": "Customers who ordered Margherita Pizza",
    "difficulty": "Advanced",
    "description": "List customers who have ordered a Margherita Pizza.",
    "hint": "Join all tables and filter by item name.",
    "expected_sql": "SELECT DISTINCT c.name FROM customers c JOIN orders o ON c.customer_id = o.customer_id JOIN order_items oi ON o.order_id = oi.order_id JOIN menu_items m ON oi.item_id = m.item_id WHERE m.name = 'Margherita Pizza';"
  },
  {
    "id": "q27",
    "title": "Category revenue contribution",
    "difficulty": "Advanced",
    "description": "Calculate the total revenue generated by each menu item category.",
    "hint": "Join menu_items and order_items, multiply price by quantity, and GROUP BY category.",
    "expected_sql": "SELECT m.category, SUM(m.price * oi.quantity) AS total_revenue FROM menu_items m JOIN order_items oi ON m.item_id = oi.item_id GROUP BY m.category;"
  },
  {
    "id": "q28",
    "title": "Orders with high item diversity",
    "difficulty": "Advanced",
    "description": "Find orders that include items from more than one category.",
    "hint": "Join tables, GROUP BY order_id, and COUNT distinct categories.",
    "expected_sql": "SELECT o.order_id, COUNT(DISTINCT m.category) AS category_count FROM orders o JOIN order_items oi ON o.order_id = oi.order_id JOIN menu_items m ON oi.item_id = m.item_id GROUP BY o.order_id HAVING COUNT(DISTINCT m.category) > 1;"
  },
  {
    "id": "q29",
    "title": "Customer spending rank",
    "difficulty": "Advanced",
    "description": "Rank customers by their total spending (sum of order totals).",
    "hint": "Use GROUP BY on customer name, SUM, and ORDER BY.",
    "expected_sql": "SELECT c.name, SUM(o.total_amount) AS total_spent FROM customers c JOIN orders o ON c.customer_id = o.customer_id GROUP BY c.name ORDER BY total_spent DESC;"
  },
  {
    "id": "q30",
    "title": "Items with high revenue contribution",
    "difficulty": "Advanced",
    "description": "Identify menu items contributing more than 200 in total revenue (price * quantity).",
    "hint": "Join menu_items and order_items, calculate revenue, and use HAVING.",
    "expected_sql": "SELECT m.name, SUM(m.price * oi.quantity) AS total_revenue FROM menu_items m JOIN order_items oi ON m.item_id = oi.item_id GROUP BY m.name HAVING SUM(m.price * oi.quantity) > 200;"
  }
]