A curated list of high-value SQL Server interview topics, sample answers, and best practices for acing technical screenings.
SQL Server interviews probe T-SQL syntax, indexing, isolation, backup, and performance tuning. Master the topics below to answer confidently.
Interviewers assess how you design, query, secure, and tune Microsoft SQL Server databases. Expect questions on T-SQL, normalization, indexing, transactions, backup, and troubleshooting. Demonstrating both theory and hands-on skills proves you can manage production workloads.
Queries about JOIN types, window functions, CTEs, and subqueries are common. Be ready to explain execution order, write set-based solutions, and optimize with EXISTS vs. IN. Knowing how to parameterize queries protects against SQL injection and enhances plan reuse.
Expect scenarios asking which index type—clustered, non-clustered, filtered, or columnstore—fits a workload. Explain seek vs. scan, covering indexes, and maintenance overhead. Illustrate with the sys.dm_db_index_usage_stats DMV to justify adding or dropping indexes.
Questions often cover isolation levels, deadlock detection, and blocking analysis. Clarify the differences between READ COMMITTED, SNAPSHOT, and SERIALIZABLE. Show how to use sys.dm_tran_locks and deadlock graphs to resolve issues without hurting throughput.
Interviewers verify you understand full, differential, and log backups, the recovery model, and point-in-time restore. Detail the impact of bulk-logged operations and demonstrate scripting with BACKUP DATABASE and RESTORE VERIFYONLY.
You may be asked to interpret execution plans, use SET STATISTICS IO, and tune with missing-index hints. Explain wait statistics, tempdb contention, and parameter sniffing. Provide quick-win strategies such as rewriting scalar functions or adding computed columns.
Start with clarifying assumptions, outline possible root causes, and walk through investigative DMV queries. Present trade-offs and cite real incidents. Linking theory to production experiences shows depth and credibility.
Galaxy’s desktop SQL editor offers AI-assisted query generation, instant execution plans, and organized Collections of practice questions. Use its context-aware copilot to rewrite queries, compare plans, and share solutions with mentors—accelerating interview prep.
Hiring teams rely on SQL Server questions to gauge a candidate’s ability to maintain data integrity, optimize performance, and ensure availability. Poor answers can signal risky hires, while strong, experience-backed responses demonstrate readiness to own critical database workloads.
CHAR reserves fixed length, ideal for uniform codes; VARCHAR stores variable length, saving space. Use CHAR for predictable sizes and VARCHAR for flexible text.
Query sys.dm_exec_requests and sys.dm_tran_locks, or enable the Blocked Process Report. In Galaxy, run saved scripts from a Collection to spot blockers quickly.
READ COMMITTED prevents dirty reads by default, while REPEATABLE READ and SERIALIZABLE add further guarantees. For truly version-based reads, use SNAPSHOT.
Galaxy’s AI copilot explains execution plans, rewrites queries, and groups practice snippets in shareable Collections—reducing prep time.
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