8 branches of analytics, product and AI interview questions

Build a three-step funnel from an events table with conversion rates.

Live SQL · Funnels · PostgreSQL · 18 min · Hard

SQL & Data Modeling · Original Uplift question

From an events table, for each calendar date return the number of DISTINCT users active in the trailing 7 days (that date and the 6 days before it).

Live SQL · Windows · PostgreSQL · 15 min · Hard

SQL & Data Modeling · Original Uplift question

Each row is one calendar day a user logged in (no duplicates).

Live SQL · Gaps islands · PostgreSQL · 18 min · Hard

SQL & Data Modeling · Original Uplift question

Assign a session id to each event per user, starting a new session whenever the gap since the user's previous event exceeds 30 minutes.

Live SQL · Sessionization · PostgreSQL · 18 min · Hard

SQL & Data Modeling · Original Uplift question

For each signup date cohort, return the cohort size and the Day-7 retention rate: the share of users who were active exactly 7 days after signup.

Live SQL · Cohort retention · PostgreSQL · 18 min · Hard

SQL & Data Modeling · Original Uplift question

Create sessions separately for each user.

Live SQL · Funnels · PostgreSQL · 25 min · Hard

SQL & Data Modeling · Original Uplift question

Each plan_history row starts a new plan period for an account and remains effective until the next change.

Live SQL · Modeling · PostgreSQL · 22 min · Hard

SQL & Data Modeling · Original Uplift question

For every calendar date from the first through last order date, compute the trailing seven-calendar-day cancellation rate: canceled orders divided by all orders in that date and the prior six dates.

Live SQL · Windows · PostgreSQL · 22 min · Hard

SQL & Data Modeling · Original Uplift question