SQL

You know SQL. This section gets you back to sharp. Use the pages below as a progression: start with quick recall, then move through advanced patterns and optimization.

SQL refresher sections

• Quick Reference Cheat Sheet
• Fundamentals Refresher
• Window Functions
• CTEs
• Advanced Aggregation
• Common Interview Patterns
• Useful Functions and Defensive Coding
• Query Optimization Basics
• Practice Problem Index
• Resources