Database Challenges

Introduction

Database mastery separates senior from junior backend engineers. Try these.

Understanding the topic

• Write a top-10 monthly report in pure SQL with window functions.
• Add an index that turns a 4-second query into a 40-ms one — and measure with EXPLAIN.
• Migrate a column type without downtime (expand-contract).
• Implement soft delete with partial unique indexes.
• Build audit triggers that record every change to a sensitive table.