What is the best SQL practice site in 2026?

It depends on your goal. For actual SQL learning with a real tutor experience: SQL Quest (wrong-answer diagnostic, AI Coach, 200+ free challenges). For real interview questions with verified company sourcing: DataLemur or StrataScratch. For combined algorithm + SQL prep: LeetCode SQL. For an employer-recognized skills certificate: HackerRank SQL. The 'best' platform changes by what you're actually trying to accomplish — pass an interview, earn a credential, learn from zero, or grind volume on real questions.

Which SQL practice site has the best free tier?

SQL Quest. The free tier includes 200+ challenges across Easy, Medium, and Hard, the AI Coach (Claude-powered, daily quota), the full 10-axis skill radar, every sector track (finance, real estate, manufacturing), all 12 company-specific landings, and the wrong-answer diagnostic. HackerRank's individual product is also free, but the SQL track is smaller (~50 questions) and lacks the AI Coach. DataLemur and StrataScratch have substantial paywalls — most content is paid. LeetCode's free tier covers ~50-80 SQL questions, less than SQL Quest.

Is DataLemur or StrataScratch better for SQL interview prep?

Both are good for interview-question grinding with verified company provenance. DataLemur is more focused on SQL specifically; StrataScratch covers SQL + Python, which matters if you're prepping for a data scientist role that tests both. DataLemur has Nick Singh's solution videos. StrataScratch has a larger total question count. Either one works for interview cram sessions, though both share the same gap: when your query is wrong, neither tells you why specifically — they show the expected output and let you compare manually. SQL Quest's wrong-answer diagnostic addresses that gap.

Is LeetCode good for SQL interviews?

LeetCode is good for general coding interview prep. The SQL track (~250 problems) is solid for syntax fluency, but SQL is one of many tracks on the platform, not the focus. If your interview is SQL-heavy (BI analyst, data engineer, analytics engineer, data scientist), a SQL-specialized platform like SQL Quest gives a tighter feedback loop. If your interview tests algorithms + SQL + system design, LeetCode is the natural choice for the algorithm rounds and reasonable for SQL too. Many candidates use both.

Should I get the HackerRank SQL Skills Certification?

It's a nice-to-have, not a substitute for actual interview readiness. The certification (Basic / Intermediate / Advanced) is recognized by some employers, especially companies that already use HackerRank for their assessments. It signals familiarity with SQL syntax. Hiring managers consistently say it doesn't replace strong portfolio or interview performance. Useful for resume filtering; less useful for actually passing interviews. If you have the time, get it AND build real proficiency on a learning-loop platform like SQL Quest.

What is wrong-answer diagnostic and why does it matter?

Most SQL practice platforms tell you 'wrong' or 'incorrect' and show you the expected output table. You compare two grids manually to find the diff. SQL Quest's wrong-answer diagnostic instead tells you specifically: 'Row 3, column total_revenue, your value is 4,820 — expected 4,920. You included refunded orders.' One line, problem identified. This dramatically tightens the practice loop — you learn why you're wrong, not just that you're wrong. After 50 problems, you've actually internalized the patterns instead of just gotten faster at staring at red X marks.

How much should I pay for SQL practice?

Most candidates ship interviews on free tiers alone if they pick the right platform. SQL Quest's free tier (200+ challenges + AI Coach) covers 90% of what most users need. Pro ($19/mo, $99/yr, $199 lifetime) unlocks unlimited AI Coach and Hard mock interviews — useful in the final 2-4 weeks before an interview. Paying $39/mo for StrataScratch or $35/mo for LeetCode Premium makes sense if you have a specific goal (Python prep, algorithm bank). Don't pay for multiple platforms simultaneously unless you're prepping full-time for 6+ weeks.

Updated May 2026 · Honest analysis

SQL Practice Sites Compared
2026 — pick by your goal

Five platforms cover most SQL learning and interview-prep traffic in 2026: SQL Quest, DataLemur, StrataScratch, LeetCode SQL, HackerRank SQL. Each one optimizes for a different job-to-be-done. This is the side-by-side that helps you pick — including where each competitor genuinely wins.

Jump to comparison matrix ↓ Decision tree

Disclosure: SQL Quest is one of the platforms compared. We've tried to flag every place a competitor wins.

The 5 Platforms

One-paragraph verdict per platform

Each card has a tagline, a summary, the candidate it's best for, and a link to the full side-by-side.

⚡

SQL Quest

The learning-loop platform with a tutor experience

200+ free challenges, AI Coach (Claude-powered) that explains why your query is wrong, 10-axis adaptive skill radar, session memory, wrong-answer diagnostic that tells you which row mismatched and why. Built for actual SQL learning — not just question grinding or certificate completion.

Best for: Anyone who wants a real tutor experience. People learning SQL from zero. Candidates stuck staring at "incorrect" with no diagnosis. Free tier covers 90% of most prep journeys.

Try SQL Quest free →

📚

DataLemur

Curated bank of real interview questions

Real SQL interview questions sourced from Meta, Google, Amazon, and other tier-1 companies, with verified provenance. Solution videos by Nick Singh (Ace the Data Science Interview). Free tier ~30-50 questions, Premium ~$29/month or $69 lifetime. No AI tutor; standard "wrong, try again" feedback loop.

Best for: Final 1-2 weeks before a Meta/Google/Amazon onsite. Candidates who learn well from solution videos. People deep in Nick Singh's content ecosystem.

Full SQL Quest vs DataLemur →

🔬

StrataScratch

Largest curated bank, SQL + Python

500-700+ questions across SQL and Python, sourced from real interviews. Aggressive paywall — free tier ~50 questions, Premium ~$39/month or $159/year. Strong for data scientist roles that test both languages. No AI tutor or wrong-answer diagnostic.

Best for: Data scientist candidates prepping SQL + Python in one platform. People who've already exhausted SQL Quest's 200 challenges and want pure volume.

Full SQL Quest vs StrataScratch →

🧮

LeetCode SQL

General coding platform with a SQL section

~250+ SQL problems within LeetCode's broader algorithm/DS/system-design platform. Free tier ~50-80 SQL questions, Premium ~$35/month covers the entire platform. Industry-standard brand, huge active community. SQL is one track among many — no SQL-specialized tutor experience.

Best for: Software engineer candidates doing combined algorithm + SQL prep. People already on LeetCode for the algorithm bank who want SQL in the same tab.

Full SQL Quest vs LeetCode SQL →

📜

HackerRank SQL

Free + skills certificate

~50 SQL questions plus the SQL Skills Certification (Basic / Intermediate / Advanced) — free for individuals. Industry-standard for employer assessments — many companies use HackerRank to screen candidates. Cert recognized on resumes, but doesn't substitute for actual interview readiness.

Best for: Early-career candidates wanting a credential. Anyone applying to companies that use HackerRank for assessments. Certificate-driven motivation.

Full SQL Quest vs HackerRank SQL →

The Full Matrix

12 features across 5 platforms

Verified May 2026. Mobile users — swipe horizontally on the matrix.

Feature

SQL Quest

DataLemur

StrataScratch

LeetCode SQL

HackerRank

Wrong-answer diagnostic (why your query is wrong)

✓

✗

AI Coach in editor (plain-English Q&A)

✓ Claude

✗

Adaptive learning path

✓ Coach picks next step

✗ Flat list

✗ Linear

Skill radar / weakness map

✓ 10-axis

✗ Tags only

✗ Counts

Badges

Free-tier challenge count

200+

~30-50

~50

~50-80

~50

Total questions (paid tier)

200+

~150

500-700+ SQL+Python

~250 SQL

~50

Real interview questions

Patterned

✓ Verified

Curated

✗ Mostly drills

Solution videos

AI-text

✓ Nick Singh

Some

Editorial

Hint button

Beginner path (zero → first SELECT)

✓ 6-step path

✗

Tutorials

Skills certificate

✗

✓ Basic/Int/Adv

No-signup to start

✓

✗

Lifetime pricing

✓ $199

✓ ~$69

✗

Free

Pricing and features change — check each platform's site for the latest. Last verified May 2026.

Decision Tree

Pick by your situation

Answer one question. Pick the platform.

"I'm learning SQL from zero — never written a SELECT statement."

Pick: SQL Quest. The 6-step path with placement check, AI Coach explaining concepts in plain English, foundational skill floor that prevents getting pushed into Hard challenges before you're ready. Other platforms assume SQL knowledge.

"I know SQL basics. I'm prepping for a Meta/Google/Amazon interview in 1-2 weeks."

Pick: DataLemur or StrataScratch for the verified-provenance question bank. Use SQL Quest's free tier as a tutor when you get stuck — paste any DataLemur question into the AI Coach for diagnosis.

"I'm prepping for a software engineer role with algorithms + SQL."

Pick: LeetCode for the algorithm bank (industry standard). Use SQL Quest's free tier for the SQL round — the diagnostic loop teaches faster than LeetCode's "Wrong Answer + expected output."

"I'm a data scientist candidate — interviews test both SQL and Python."

Pick: StrataScratch for the combined SQL + Python question bank. SQL Quest's free tier for SQL specifically when you want diagnostic feedback.

"I want a credential to put on my LinkedIn / resume."

Pick: HackerRank for the SQL Skills Certification. A few hours of work for the credential. Then build real proficiency on SQL Quest.

"I want one platform that handles my whole prep, free tier, no paywall."

Pick: SQL Quest. 200+ challenges across all difficulties, AI Coach, skill radar, sector tracks, all 12 company landings — all free. No other platform's free tier covers this much ground.

"I'm stuck. I keep getting 'incorrect' and don't know what's wrong with my queries."

Pick: SQL Quest. The wrong-answer diagnostic was built for exactly this scenario. Specific row + column + value + reason, not just "incorrect, try again."

"I want to use a platform that the company I'm applying to also uses."

Pick: HackerRank if they use HackerRank for assessments. Familiarity with the same UI on assessment day matters. After that, switch to SQL Quest for the actual learning.

Pricing

All 5 platforms at a glance

Most candidates can ship interviews on free tiers if they pick the right platform.

SQL Quest

200+ FREE

$19/mo · $99/yr

$199 lifetime

Free tier covers 90% of most prep. Pro adds unlimited AI Coach + Hard mock interviews.

DataLemur

~30-50 FREE

~$29/mo

~$69 lifetime

Cheapest lifetime. No AI tutor included at any tier.

StrataScratch

~50 FREE

~$39/mo · ~$159/yr

No lifetime

SQL + Python combined. Most expensive monthly.

LeetCode SQL

~50-80 FREE

~$35/mo · ~$159/yr

No lifetime

Premium covers all tracks (algorithms, DS, system design, SQL). You pay for the whole platform.

HackerRank SQL

FREE

Free for individuals

Cert: free

B2B revenue (employer assessments). Free is the whole product for individuals.

SQL Practice Sites Compared
2026 — pick by your goal

One-paragraph verdict per platform

12 features across 5 platforms

Pick by your situation

All 5 platforms at a glance

Frequently asked

Try the diagnostic loop
before you decide.

SQL Practice Sites Compared2026 — pick by your goal

One-paragraph verdict per platform

12 features across 5 platforms

Pick by your situation

All 5 platforms at a glance

Frequently asked

Try the diagnostic loopbefore you decide.

SQL Practice Sites Compared
2026 — pick by your goal

Try the diagnostic loop
before you decide.