Career
The SQL Interview Toolkit
Senior Data Analyst
April 5, 2026
7 min read
Top Interview Patterns
1. **Find duplicates**: GROUP BY + HAVING COUNT > 1.
2. **Find Nth highest salary**: Window functions or subqueries.
3. **Cumulative sum**: SUM() OVER (ORDER BY ...).
4. **Find missing records**: LEFT JOIN + WHERE IS NULL.
5. **Pivot data**: CASE WHEN + GROUP BY.
Pro Tip
Practice on platforms like LeetCode, HackerRank, and StrataScratch.
*Day 96: Building a Data Dictionary.*