Data Scientist Data Manipulation (SQL/Python) Interview Questions
Practice 530 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"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"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."
"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."
"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"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."
Identify SQL Joins and Correct Query Errors
Winner +----+-------+ | ID | Name | +----+-------+ | 1 | Alice | | 2 | Bob | | 3 | Carol | +----+-------+ Loser +----+-------+ | ID | Name | ...
Write SQL for multi-account metrics
A consumer app allows one user to own multiple accounts. Use SQL to answer the following questions. Assume the database has these tables: accounts - a...
Analyze Monthly Prime vs Non-Prime Sales and Price Buckets
sales +-----------+------------+----------+-------+ | order_id | order_date | is_prime | price | +-----------+------------+----------+-------+ | 1001...
Calculate Day-7 Retention Rate from User Post Data
post_activity +---------+------------+-------+ | user_id | post_date | posts | +---------+------------+-------+ | 1 | 2023-01-01 | 3 | | 1 ...
Compute DAU and rolling MAU with zero days
You have two tables in PostgreSQL: Tables users - user_id (STRING / INT, PK) - signup_date (DATE) logins - user_id (STRING / INT, FK → users.user_id) ...
Write conditional aggregates with CASE WHEN
Write a query that produces conditional aggregates using CASE WHEN (e.g., counts of approved vs declined transactions per merchant and the sum of amou...
Compute 30-day power users and 7-day retention
You are interviewing for a Product/Risk Data Scientist role at a crypto exchange. Assume all timestamps are in UTC. Tables `sql trades( user_id ...
Write SQL for character safety and engagement metrics
You are working with a conversational product that has users, AI characters, and conversations. Write SQL queries for each of the tasks below. Assume ...
Write SQL for CTR and Revenue
You are given the following tables: ads( ad_id BIGINT, advertiser_id BIGINT, ad_type VARCHAR, -- values include direct and brand ad...
Analyze Global Engagement and Impressions with SQL Queries
impressions +---------+---------+----------+----------------+ | user_id | country | category | impression_cnt | +---------+---------+----------+------...
Find recommended friend pairs by shared songs
You work on a music app and want to recommend “friend” connections based on listening similarity. Assume the following tables (all timestamps are in U...
Generate binomial matrix and column-normalize
Using Python with NumPy, generate a 100×100 matrix of Binomial(n = 10, p = 0.3) draws with a fixed random seed, then normalize each column so it sums ...
Write dating profile report with final reviews
Today is 2025-09-01. You need a daily dating-profile quality and engagement report that only includes profiles whose latest version has a final approv...
Write SQL filtering, grouping, CASE, UNION tasks
Use the following schema and sample data to answer all parts. Assume standard ANSI SQL and that amounts are DECIMAL. Table: orders +----------+-------...
Select max-discount product per category
You have a catalog of products. For each category, return exactly one product: the one with the largest absolute discount; if multiple products in the...
Write SQL to verify quarterly sales decline
You are given a single dataset for a beverage company and must decide whether Q2 2024 truly declined. Write one standard SQL query that produces a com...
Append country tables and rank salaries in USD
You have separate country-level employee tables that must be appended and ranked by salary converted to USD using an exchange rate table. SQL schema a...
Compute rolling cold-delivery rates with windows
Assume a food-delivery platform with the following schema. Use PostgreSQL. A delivery is considered "cold" if food_temp_c < 40 at dropoff OR there is ...
Compute monthly CRR with merges and gaps
You are given PostgreSQL tables user_profile(user_id, signup_ts, country, is_employee, is_test), user_events(user_id, event_ts, event_type, revenue, p...
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...