Coinbase Data Scientist Data Manipulation (SQL/Python) Interview Questions
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Calculate Adoption and Transaction Rates, Identify Cross-Region Sales
user_txn +---------+-------------+------------+---------------+------------------+---------------------+ | user_id | user_region | adopted_at | transa...
Calculate Cumulative Sum for Each Integer in Table
numbers +-----+ | num | +-----+ | 1 | | 2 | | 13 | | 14 | | 15 | +-----+ Scenario You have a table containing one integer per row; for each row...
Compute adoption, latency, and cross-region transactions
Invented schema: users(user_id INT PRIMARY KEY, user_region STRING, adopted_at TIMESTAMP NULL) transactions(txn_id INT PRIMARY KEY, user_id INT, txn_t...
Write SQL: sum values ≤ each row’s value
Given table numbers(id INT PRIMARY KEY, val INT), return for every row the sum of all val across the entire table that are ≤ that row’s val (i.e., com...
Write SQL and Python for funnels/retention
Given the following schema and small samples, answer Parts A–C. Assume timestamps are UTC and "today" is 2025-09-01. Schema: users(id INT, country STR...