DataBrighten

    SQL practice questions with answers

    8 questionswith checked answers ยท sample sql database

    GROUP BY, JOIN, LEFT JOIN and filters on a four-table store database. Updated 3 November 2026.

    textnumberdateyes/no

    Steps

    1. Download store-database.sql.
    2. Load it: sqlite3 store.db < store-database.sql (or run it in pgAdmin, MySQL Workbench or DBeaver).
    3. Write each query, then open the answer to compare your result and our SQL.

    Questions

    try first, then open the answer

    Revenue by product category, excluding cancelled and returned orders?

    Technology $537,612.64; Furniture $200,325.49; Office Supplies $67,416.80

    SQL

    SELECT p.category, ROUND(SUM(i.quantity*i.unit_price),2) AS revenue
FROM order_items i
JOIN orders o ON o.order_id = i.order_id
JOIN products p ON p.product_id = i.product_id
WHERE o.status NOT IN ('Cancelled','Returned')
GROUP BY p.category
ORDER BY revenue DESC

    File: store-database

    Top 5 customers by revenue (excluding cancelled and returned orders)?

    Steven Lewis (CU10118) $21,983.66; Patricia Khan (CU10105) $15,506.69; Elizabeth Flores (CU10237) $14,375.98; Mei Nelson (CU10039) $14,273.55; Carol Clark (CU10292) $14,080.03

    SQL

    SELECT c.customer_id, c.first_name || ' ' || c.last_name AS name, ROUND(SUM(i.quantity*i.unit_price),2) AS revenue
FROM customers c
JOIN orders o ON o.customer_id = c.customer_id
JOIN order_items i ON i.order_id = o.order_id
WHERE o.status NOT IN ('Cancelled','Returned')
GROUP BY c.customer_id, name
ORDER BY revenue DESC
LIMIT 5

    File: store-database

    How many customers have never placed an order?

    8 customers

    SQL

    SELECT COUNT(*)
FROM customers c
LEFT JOIN orders o ON o.customer_id = c.customer_id
WHERE o.order_id IS NULL

    File: store-database

    Orders by status?

    Delivered 804; Shipped 66; Cancelled 51; Processing 47; Returned 32

    SQL

    SELECT status, COUNT(*) FROM orders GROUP BY status ORDER BY COUNT(*) DESC

    File: store-database

    What is the list price of product P0012?

    Corner Bookcase, $188.81

    SQL

    SELECT product_name, unit_price FROM products WHERE product_id = 'P0012'

    File: store-database

    Which region has the highest sales?

    South, $299,380.41 (Midwest $234,801.89, West $217,262.68, Northeast $204,168.78)

    SQL

    SELECT region, ROUND(SUM(sales),2) AS total FROM sales_orders GROUP BY region ORDER BY total DESC, region

    File: sales-orders-1000

    Profit margin (profit / sales) by category?

    Office Supplies 26.98%; Technology 22.32%; Furniture 21.42%

    SQL

    SELECT category, ROUND(SUM(profit)/SUM(sales)*100,2) AS margin_pct FROM sales_orders GROUP BY category ORDER BY margin_pct DESC, category

    File: sales-orders-1000

    Average wait (seconds) and resolution rate by queue?

    Billing 100.8 s, 86.2% resolved; Returns 103.3 s, 87.6% resolved; Sales 100.7 s, 85.7% resolved; Technical 112.8 s, 67.9% resolved

    SQL

    SELECT queue, ROUND(AVG(wait_seconds),1), ROUND(100.0*SUM(resolved)/COUNT(*),1) FROM call_center GROUP BY queue ORDER BY queue

    File: call-center-1000