Best SQL Practice Websites 2026
Free + Paid — 5 Platforms Tested

Curated bank of real interview questions, with verified provenance

DataLemur places second on the strength of its real interview question bank. Nick Singh (author of Ace the Data Science Interview) curates questions with verified company sourcing — when DataLemur labels a problem "Meta SQL interview," there's high confidence it actually was. The Premium bank — its pricing page lists 100+ SQL interview questions plus 70+ data-science questions, and 250+ on the lifetime plan (as listed 2026-09-07) — is smaller than StrataScratch's, but the curation quality is consistently strong, and the solution videos by Nick Singh are valuable for video-first learners. The free tier's question count is not published on the pricing page (checked 2026-09-07) — treat it as a sample to evaluate with, not a bank to prep on.

The acknowledged weakness: the standard "incorrect, here's the expected output" feedback loop. When your query is wrong, DataLemur shows you the expected table and lets you compare manually. There's no AI tutor, no Skillmap, no adaptive path. It's a question library, not a learning loop. Many DataLemur users hit this exact gap and supplement with SQL Quest's free tier as their tutor.

General coding platform with a deep SQL section

LeetCode's Database section has roughly 250 SQL problems, which is solid pattern coverage for an interview track. The platform's huge community generates active discussion threads, and the brand carries weight on resumes ("solved 200 LeetCode problems" is a hiring signal in some loops). The Premium tier ($35/mo or $159/yr) covers all of LeetCode — algorithms, data structures, system design, and SQL — making it a strong fit for software engineer or data engineer candidates with combined prep needs.

The weakness: SQL is one track among many, not the focus. The feedback loop is "Wrong Answer + expected output" with no SQL-specialized diagnostic, no Skillmap, no AI tutor that reads your schema. The interface is optimized for general coding, not for SQL specifics like schema visualization or progressive hints. If you only care about SQL, you're paying $35/mo for an algorithm bank you don't use. The free tier (~50-80 SQL questions) is reasonable, but again no SQL-specific tutoring.

The largest combined SQL + Python interview question bank

StrataScratch has the largest raw question count of any platform reviewed — 1000+ coding questions across SQL, Python and R, plus 500+ ML, statistics and system-design questions and 50+ data projects (as listed on platform.stratascratch.com/pricing, 2026-09-07), sourced from real interviews with reasonable provenance claims. For data scientist candidates specifically, the combined-language coverage is genuinely valuable: you prep both languages in one tool. Question quality is solid, with consistent curation.

The weakness lowering its rank: most of the bank is paid. The free plan is 75+ questions with hints and solutions (as listed 2026-09-07) — a fair first pass, but the other 900+ questions, the projects and every AI feature sit on Premium, and even the free plan needs an account. Premium is $19/month, $97.30/year or $202.30 lifetime as listed on platform.stratascratch.com/pricing on 2026-09-07, the yearly and lifetime shown with a 30% promotion off $139 and $289 — no longer the expensive option it once was. Like DataLemur and LeetCode, no wrong-answer diagnostic and no Skillmap; its AI guidance and AI mock interviews are Premium-only. If you want question volume on real interview questions and don't need diagnostic feedback, StrataScratch is solid — but most candidates we've talked to who used StrataScratch heavily ended up supplementing with another tool when stuck.

Free + a recognizable skills certificate

HackerRank's SQL track is free for individuals with roughly 50 questions and an SQL Skills Certification (Basic / Intermediate / Advanced) that some employers recognize. The platform's main commercial use is B2B — many companies use HackerRank to screen candidates with their own assessments — which means practicing on HackerRank gives you UI familiarity for assessment day. The cert is a reasonable credential to put on LinkedIn, particularly for early-career candidates building a resume signal.

The weakness placing it last: question depth is shallow on the SQL track specifically. ~50 questions is the smallest of any platform reviewed, and the focus is syntax fluency rather than interview-pattern depth. No AI tutor, no wrong-answer diagnostic, no Skillmap. The "Wrong Answer" feedback loop is generic. If your goal is the certificate or assessment-day familiarity, HackerRank is the right pick — but it shouldn't be your only prep tool.