Decision Table Lookups

A decision table is a data structure that captures business rules as data rather than code. Each row represents a combination of conditions and the resulting action. Decision tables make complex rules explicit, easy to modify, and simple to test. This approach separates the rules themselves from the logic that applies them, enabling non-programmers to review and validate the business logic. This pattern is essential when business logic changes frequently. Instead of modifying if-elif chains (and risking bugs), you update the decision table. Non-programmers can even review and validate the rules. Basic Decision Table Define rules as a list of tuples or dictionaries containing conditions and outcomes. The table is checked top to bottom, and the first matching rule wins. This makes rule prior

About This Interactive Section

This section is part of the Control Flow: Advanced lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

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DataDriven combines four interview rounds (SQL, Python, Data Modeling, Pipeline Architecture) with adaptive difficulty and spaced repetition. Easy problems get harder as you improve. Weak concepts resurface until you master them. Your readiness score tracks progress across every topic interviewers test. Every lesson section ends with problems you solve by writing and running real code, not by picking multiple-choice answers.