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SQL for Testers
SQL Interview Questions for QA & SDETs
SQL questions QA interviewers actually ask — joins, subqueries, window functions, GROUP BY tricks, and test data scenarios.
- INNER, LEFT, RIGHT, FULL & SELF joins
- GROUP BY, HAVING & aggregation pitfalls
- Window functions: ROW_NUMBER, RANK, LAG
- Subqueries vs CTEs vs derived tables
- Test data generation & seeding
- Index basics & query tuning
Scenarios that catch most testers off-guard
Finding duplicates, second-highest salary, missing dates in a sequence, validating referential integrity for test data and writing data-quality checks.
Frequently asked questions
Which SQL flavor do you use?
ANSI SQL with notes for MySQL, PostgreSQL and SQL Server differences.
Do you cover query tuning?
Yes — indexes, execution plans and common anti-patterns testers see in interviews.