HackerRank SQL Practice

What it is

HackerRank's SQL domain is a set of practice challenges grouped into subdomains: Basic Select, Advanced Select, Aggregation, Basic Join, Advanced Join and Alternative Queries (source: hackerrank.com/domains/sql, as of 2026-09). Each challenge gives a table description and a question; you write the query in the browser and the site checks your output. You can filter by difficulty and status, and discussion threads show other approaches.

HackerRank also offers short skills certification tests, including an SQL (Basic) assessment of 30 minutes with two questions (source: HackerRank skills verification page, as of 2026-09).

Is it worth your time?

Yes, as a first practice set. The early Basic Select and Aggregation challenges are gentle and build confidence quickly, and the Join sections are good drills once you have learned joins. Many companies use HackerRank for online assessments, so getting used to its editor and output checking removes one source of stress on test day. The harder Advanced Select and Advanced Join problems are closer to puzzles and take real thought.

Prerequisites

None for Basic Select. Learn joins and GROUP BY before the later sections.

Free vs paid

Practice challenges and the basic skills certifications are free for individual developers. HackerRank's paid products are for companies running hiring tests.

How to use it well

• Work through a subdomain in order rather than jumping around.
• Choose the dialect closest to the database you are learning; the editor offers several.
• When the checker rejects your answer, compare your output with the expected format carefully: ordering and column formatting matter.
• Revisit any challenge you solved by looking at the discussion a week later and solve it again from memory.

Watch out for

Some problems have picky output formats, and a few rely on dialect-specific functions. If you are stuck on formatting rather than logic, read the discussion to see what the checker expects, then move on.

Common questions

Is the certificate worth adding to my profile? It is a small signal. Projects and the ability to explain your queries matter more.

How many problems should I do? Enough to solve each subdomain's medium problems without help, rather than a target number.