Get help with a course, a practice problem, a PDF order or a collaboration.

Your PDF is emailed to the address you entered at checkout, usually within a few minutes. If it hasn’t arrived within an hour, check your spam folder, then write to us with your payment email and transaction ID and we’ll resend it. See the Shipping & Delivery Policy.

Because PDFs are delivered instantly, purchases are generally non-refundable. We do refund duplicate payments, failed deliveries we can’t fix, and files that are corrupted. Details are in the Refund & Cancellation Policy.

Progress is saved to your account when you’re logged in. Questions you solved as a guest are stored in that browser and sync the next time you log in on it. If something still looks wrong, send us your account email and the practice area (SQL, Python, DSA, DAX or PySpark).

Thank you — please pick “Report an error” above and include the page link, the topic or question title, and what you expected. We check every report and fix confirmed issues quickly.

Yes. Choose “Collaboration or sponsorship” or “Corporate training” and tell us about your audience, the topics (SQL, Python, Power BI, Snowflake, Databricks, Spark, Gen AI) and your timeline. You can also reach Shubham Singh Rao on LinkedIn.