SQL Interview Mastery — 100 Questions & Answers
Are you preparing for a Data Analyst, Data Engineer, or Backend Developer interview?
SQL is asked in almost every data role interview — and most candidates fail not because they can't write queries, but because they lack depth in theory, get caught off-guard by edge cases, or can't explain their thinking clearly.
This ebook fixes all of that.
📦 What's Inside
100 carefully chosen SQL interview questions with complete, detailed answers — organized across 6 chapters:
Chapter 1 — SQL Fundamentals (Q1–Q15) DDL vs DML, SQL execution order, WHERE vs HAVING, NULLs, constraints, data types, aggregate functions, UNION vs UNION ALL
Chapter 2 — Joins & Subqueries (Q16–Q30) INNER, LEFT, RIGHT, FULL, CROSS, SELF joins — with real query examples. IN vs EXISTS vs JOIN, correlated subqueries, set operations
Chapter 3 — Window Functions (Q31–Q45) The most asked advanced topic in modern SQL interviews. ROW_NUMBER, RANK, DENSE_RANK, NTILE, LAG, LEAD, FIRST_VALUE, rolling averages, cumulative sums, streak detection
Chapter 4 — Advanced SQL Concepts (Q46–Q65) Recursive CTEs, normalization (1NF to BCNF), indexes (clustered vs non-clustered), ACID properties, isolation levels, views, materialized views, triggers, OLTP vs OLAP, Star vs Snowflake schema, PIVOT, MERGE/UPSERT
Chapter 5 — Real Interview Query Bank (Q66–Q85) 20 real-world query challenges: cohort analysis, churn detection, Pareto/80-20 analysis, median salary, pivot by quarter, retention rate, week-over-week growth, session analysis
Chapter 6 — Strategy & Best Practices (Q86–Q100) Query optimization checklist, anti-patterns to avoid, SCD Types 1/2/3, production SQL best practices, and smart questions to ask the interviewer that will make you memorable
✅ Every question includes:
- A complete, accurate answer
- Working SQL code examples where applicable
- 💡 Interview Tip boxes — the specific details that turn a 7/10 answer into a 10/10
👤 Who is this for?
- Freshers preparing for their first data role interview
- Working professionals targeting a switch to Data Engineering or Analytics
- Experienced engineers brushing up for senior-level interviews
- Anyone who wants to go from writing SQL to confidently explaining SQL
🎯 Topics Covered
Window Functions · Joins · CTEs · Recursive Queries · Subqueries · Indexing · ACID · Transactions · Normalization · Query Optimization · OLTP vs OLAP · Data Warehouse Design · Pivot & Unpivot · SCD · MERGE · Cohort Analysis · Churn Detection · Interview Strategy
📄 Format: PDF — instant download, works on mobile and desktop 🌐 Language: English 📊 Level: Beginner to Advanced 🔢 Questions: 100 with full answers
💰 Price: ₹100 One-time payment. No subscription. Download and keep forever.
⭐ Why buy this over free resources?
Free resources give you scattered questions. This ebook gives you a structured, complete preparation path — from core concepts to real-world challenges to interview strategy — in one place, for the price of a cup of coffee.