In-Memory SQL / Database Implementation

Problem Overview

Implement an in-memory SQL-like database from scratch with no external frameworks. You are given (or must design) a DB class and must progressively implement the following functionality across 3–4 parts: Part 1 – INSERT + basic SELECT (projection): Implement insert(table_name, row_dict) to add rows and query(table_name, columns) to return only…

• 7 candidate-reported follow-ups — the exact probes interviewers asked, with the trigger for each
• The rest of the problem statement — full requirements, constraints, and edge cases
• Approach and trade-offs — what passing candidates did, and the mistakes that sink people