SQL questions from Walmart data engineering interviews.
These sql questions are sourced from Walmart data engineering interviews. Each includes an expert-level answer. This set leans toward the medium-difficulty band most real interviews actually live in (3 of 6). Recurring themes are partition, join, and optimization — these patterns appear most often in real interviews and reward the deepest preparation. Average answer is around 1 minute of reading — plan roughly 1 hour to work through the full set thoughtfully.
This collection contains 6 curated questions: 1 easy, 3 medium, and 2 hard. The distribution skews toward harder problems, reflecting the depth expected in senior-level interviews.
The most frequently tested areas in this set are partition (4), join (3), optimization (2), sql (2), etl (1), and spark (1). Focusing on these topics will give you the highest return on your preparation time.
Start with the easy questions to warm up and solidify fundamentals. Medium-difficulty questions form the bulk of real interviews — spend the most time here and practice explaining your reasoning out loud. Hard questions often appear in senior and staff-level rounds; attempt them after you're comfortable with the basics. For each question, try answering before revealing the solution. Use our AI Mock Interview to simulate real interview conditions and get instant feedback on your responses.
Data Warehouse Design from scratch
Finding nth Highest Salary within each department
Normalization & Slowly Changing Dimensions (SCD) Type 2
Optimizing Spark Jobs when they take longer than expected
SQL Query Design: employees with highest salaries within each department
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