Other Data Scientist Data Manipulation (SQL/Python) Interview Questions
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Solve window-function SQL without joins
You must use only window functions (no JOINs). CTEs are allowed. Given the schemas and tiny samples below, write SQL for each sub-question and explain...
Build SQL pivot with lookups and currency conversion
You are given the following schema and sample data. Use SQL (or Python with SQL-like transforms) to answer the tasks below. Treat amounts as gross rev...
Write SQL to analyze response accuracy and speed
You are given response-level data for an online assessment with sections verbal/design/analytics and verbal subtypes grammar/vocab/tense/other. Using ...
Design MapReduce and Spark jobs
Big data systems: (a) Explain Hadoop’s fault tolerance (HDFS replication, task re-execution) and why MapReduce includes shuffling and sorting; in a wo...
Manipulate data efficiently in Python
Answer the following: (a) Contrast list comprehensions and generators with respect to memory and evaluation; write a generator that yields rolling win...
Query conversion and retention with SQL windows
Schema and sample data (PostgreSQL): users(id, signup_date, country) 1 | 2025-08-20 | US 2 | 2025-08-25 | US 3 | 2025-08-27 | CA 4 | 2025-08-30 | US 5...
Diagnose zero IE uploads with SQL
On 2025‑09‑01 ('today'), the dashboard shows image uploads for Internet Explorer (IE) dropped to zero. Write SQL to (a) determine if this is a technic...