Crack Any Data Engineering SQL Interview | Practical Questions & Solutions | Live #5

Session 5 of the Data Engineering Roadmap — and this one is ALL about cracking your SQL interview! After 4 sessions of building your SQL foundation, today we put it all together with the most frequently asked PRACTICAL SQL questions in real Data Engineering interviews. No theory. Just real questions. Real solutions. Real jobs. ───────────────────────────────────────── 📌 WHAT WE SOLVE LIVE: ───────────────────────────────────────── 🔗 JOIN Questions: ✅ Find employees with no matching orders (NULL joins trap) ✅ Self-join to find employees earning more than their manager ✅ Multi-table joins with filtering logic 🪟 WINDOW FUNCTION Questions: ✅ 2nd highest salary per department (no LIMIT!) ✅ Running totals & moving averages ✅ Gaps and islands problems with ROW_NUMBER 📊 GROUP BY & Aggregation Questions: ✅ Departments where avg salary "Greater Than" company average ✅ Monthly active users with GROUP BY + HAVING ✅ Duplicate detection & deduplication 📦 CTE Questions: ✅ Running total of sales by month using CTE ✅ Recursive CTE for org hierarchy traversal ✅ Chained CTEs for multi-step transformations 🔎 SUBQUERY Questions: ✅ Products priced above category average ✅ Correlated subquery vs CTE — which is faster? ✅ EXISTS vs IN — the interview trap ───────────────────────────────────────── 💡 WHY WATCH THIS? ───────────────────────────────────────── → 40+ real questions from top companies → Each question solved step-by-step with explanation → Understand WHY each approach works (not just memorize) → Time & space complexity discussed for each solution → Common mistakes interviewers catch — and how to avoid them