Crack The Finance SQL Interviews: Stop Studying Retail Models

If you want to fail a Staff Data Engineer interview at a hedge fund, investment bank, or trading platform, do this: walk up to the whiteboard and draw an e-commerce shopping cart schema. I have interviewed dozens of engineers who flawlessly explain how to link Users to Orders and Products. The problem? Financial markets do not have shopping carts. In retail, an order is a static event. In finance, an order is a living, breathing entity that gets partially filled, canceled, amended, split, and repriced across milliseconds. This is my contrarian take for anyone preparing for data modeling and SQL interviews in the FinTech space: Stop memorizing retail Kimball models. Finance is about tracking state over time, immutability, and calculating risk at scale. Let’s break down the exact concepts, SQL aggregations, and data models you must master to crack the interview and operate at a Staff level.