Custom SQL Practice

Describe a problem

JOINs Window functions GROUP BY / HAVING Recursive CTE Self-join

Rows per table:

Pick a company & role

Company

Role

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Problems are grounded in researched profiles of each company's actual SQL interview patterns, data domain, and stack (when a profile exists for the selection). First generation hits the API; subsequent loads come from your browser's local cache.

Learn a SQL concept

Window functions LAG / LEAD CTEs Recursive CTEs JOINs GROUP BY / HAVING Self-joins Subqueries CASE / Pivot Date functions Sessionization Top N per group Running totals NULL handling

A focused lesson loads in the chat below, with a small practice problem above so you can apply what you learn.

Spaced repetition queue

Every problem you attempt is auto-saved here. Items resurface on a schedule that adapts to how well you did — got it cold = longer wait, needed hints or solution = sooner. The fastest path to interview-ready.

Due now

Coming up (next 7 days)

Timed mock interview

Practice under realistic pressure. The AI plays your interviewer — answers clarifying questions, listens to you talk through your approach, and gives feedback at the end.

Duration

Source

🔊 Speak the problem aloud (text-to-speech) 🎙 Listen when I press the mic button (speech-to-text) 🔊 Speak interviewer replies aloud

During the mock: type SQL on the right, talk through your approach with the mic, ask the interviewer clarifying questions in the chat below. Time's up triggers an auto-critique.

Ask about this problem

Ask follow-up questions about the current problem here.

Results

Run a query to see results.