Question 1

How does in-browser SQL execution work?

Accepted Answer

DB Exercises uses WebAssembly (PGlite for PostgreSQL 16). The actual PostgreSQL database engine compiles to WebAssembly and runs directly inside your browser sandbox. Your queries execute locally in 3–5 milliseconds without transmitting data to any remote server.

Question 2

Is there a free trial for Pro?

Accepted Answer

Yes! We offer a full 7-day free trial on our Pro plan. You can practice all advanced business tracks, Window Functions, and CTEs immediately with zero upfront charges.

Question 3

Do my database queries touch your servers?

Accepted Answer

No. Because execution is 100% client-side via WebAssembly, your queries and schema tables remain completely private within your local browser. There is zero server execution logging or data interception.

Question 4

Why do we use PostgreSQL 16 for practice?

Accepted Answer

PostgreSQL is the world's most popular and powerful open-source relational database. It adheres closely to the ANSI SQL standard while offering modern capabilities like Common Table Expressions (WITH), Window Functions, and JSONB operators (->>). By learning PostgreSQL, your queries transfer seamlessly to Postgres, Snowflake, Redshift, BigQuery, and other modern SQL data warehouses.

Question 5

Can I cancel my membership anytime?

Accepted Answer

Yes, you can cancel your subscription with a single click at any time from your account settings. You will retain Pro access through the end of your billing cycle. We also offer a 14-day no-questions-asked money-back guarantee.

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