Data Scientist Data Manipulation (SQL/Python) Interview Questions
Practice 550 real Data Manipulation (SQL/Python) interview questions for Data Scientist roles. From companies including Meta, Amazon, TikTok, Capital One, DoorDash.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
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"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
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"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Analyze Pirated Theme Usage
This question evaluates competency in temporal data manipulation, interval-overlap logic, aggregations and joins to calculate monthly usage metrics an...
Query US-based users and most active forums
You are given user and post data for an online forum platform. Tables (schemas) Assume the following tables: users - user_id BIGINT (PK) - home_countr...
Write SQL for repeat churn
Write a SQL query to measure the performance of a free-month promotion experiment. Assume experiment_users already contains only users who were eligib...
Compute Heavy-Caller Percentages
You are given two tables that track voice calls and daily active users for a messaging app. Table: call_events - call_id BIGINT — unique call identifi...
Solve SQL and Python OA tasks
Complete the following two online-assessment tasks. Task A — SQL You are given two tables: customer - customer_id INT - customer_name VARCHAR - purcha...
Compute signup rate and retention from raw logs
Scenario You are analyzing an A/B test for a marketing campaign offering a free 1-month trial. You are given raw “upstream” tables that resemble produ...
Implement robust word counts and min/max
You receive a 50GB UTF-8 text corpus on disk. Implement a Python solution that:\n- Streams the file without loading it fully into memory.\n- Counts ca...
Compute a Rolling Seven-Day Revenue Sum with Missing Dates
Solve a PostgreSQL rolling-revenue problem that needs a complete daily series per seller, including no-order dates. It assesses UTC date handling, gap...
Merge overlapping intervals per group in pandas
This question evaluates proficiency in time-series data manipulation and interval reasoning using pandas, including grouping, datetime handling, and i...
Clean scores and return top 5 students
This question evaluates proficiency in data cleaning and transformation for Data Science, focusing on handling missing values, median imputation, and ...
Write SQL to compute signup and retention lift
You are analyzing an A/B test for a marketing campaign that offers a free 1‑month trial. Assume all timestamps are in UTC. Tables experiment_assignmen...
Handle repeated churn in SQL
This question evaluates proficiency in time-based data manipulation and analytics, including handling repeated churn and resubscription, interval logi...
Build DID panel and compute effects in SQL
Using the schema and toy data below, write SQL to construct a user-week panel and compute a clean pre/post DID dataset for first reminder exposure. Re...
Analyze advertiser spend by source
This question evaluates proficiency in data manipulation and analytics using SQL or Python, testing skills such as joins, time-based filtering, cohort...
Measure Daily Late-Order Rates by Delivery Zone
The original interview report identified a late-order SQL exercise but did not preserve its exact schema. The following is a self-contained practice r...
Query departments and top earners
This question evaluates proficiency in relational data manipulation, including multi-table joins, grouping and aggregation to identify departments wit...
Calculate Monthly Customer Retention
Calculate Monthly Customer Retention Write one PostgreSQL SELECT statement or CTE query. Do not create, alter, or modify tables. Schema orders | colum...
Justify and harden your analytics and BI stack
List your current analytics tech suite end-to-end (ingestion, storage/warehouse, transformation, orchestration, catalog/lineage, experimentation platf...
Compare list/dict; parse JSON/CSV at scale
Compare Python list and dict precisely: for append/insert/lookup/update/delete, state average and worst-case time complexity, memory implications, and...
Calculate valid daily usage with gap constraints
Write Standard SQL to compute, for a given date (use 2025-09-01), each user's total valid usage minutes. Schema and rules: Schema (timestamps are UTC)...