SQL Mastery for SDET Interviews

Every SDET interview I've cracked started the same way:

"Open a SQL editor. Let's run through some queries."

No whiteboards. No tricks. Just whether you can think clearly under pressure.

This 27-page guide is everything I wish I'd had before my first SDET round —

100+ SQL questions curated from real interview rounds, organized across

7 progressive sections so you can build confidence one layer at a time.

📚 WHAT'S INSIDE

Section 1 — Foundations

SELECT, WHERE, NULL handling, LIKE patterns, IN, BETWEEN

Section 2 — Sorting, Aliasing & Deduplication

ORDER BY, DISTINCT, LIMIT/OFFSET, dirty-data handling

Section 3 — Joins & Set Operations

INNER, LEFT, RIGHT, FULL, CROSS, self-joins, UNION, EXCEPT, INTERSECT

Section 4 — Aggregations & Grouping

COUNT, SUM, AVG, GROUP BY, HAVING, conditional aggregates, ROLLUP

Section 5 — Subqueries & CTEs

Scalar, correlated, EXISTS, WITH clauses, recursive hierarchies

Section 6 — Window Functions

ROW_NUMBER, RANK, DENSE_RANK, LAG/LEAD, running totals, NTILE

Section 7 — Advanced SDET Patterns

Gaps & islands, pivots, median, duplicate detection, percentage calculations,

referential integrity validation — the real-world queries SDETs run daily

✨ WHAT MAKES THIS DIFFERENT

✓ Every question includes the answer AND the "gotcha" — the trap interviewers actually probe (NULL comparisons, ties, NOT IN with NULLs, etc.)

✓ Dialect notes for MySQL, PostgreSQL, SQL Server, and Oracle

✓ Progressive difficulty — start at Q1 and grow to senior-level patterns

✓ Quick cheat-sheet appendix for the night before your interview

✓ Real test-data validation queries you can use on the job

🎯 WHO THIS IS FOR

- Manual testers transitioning to SDET / QA Automation roles

- Junior SDETs preparing for mid-level interviews

- Mid-level SDETs targeting senior or lead positions

- Anyone whose SQL rounds have ever gone sideways

📥 FORMAT

27-page PDF / Word document, instantly downloadable.

Practice every query on sql-practice.com or programiz.com.

By Abhijeet Jagtap · QA Mentor

SDET Interview Prep Series