SQL Server is a database management system developed by Microsoft. It was first launched in 1989 with help from Sybase and Ashton-Tate. It was created to help businesses store and manage data easily. Over the years, SQL Server has become one of the most popular database systems in the world. Many companies, from small startups to big tech giants, use it to manage important information. Because of this demand, SQL Server skills are highly valued. To help you get ready for your interview, here is a list of 50+ commonly asked SQL Server interview questions and answers.
Fun Fact – Microsoft SQL Server holds around 27.56% of the global database market share, making it one of the top three databases.
Note – We have categorized the top SQL Server interview questions into basic-level, for freshers, experienced, advanced, scenario-based, and practical questions.
Basic Level SQL Server Interview Questions
Here are basic-level SQL Server interview questions and answers to help you build a strong foundation for your preparation.
- What is SQL Server and why is it used?
SQL Server is a relational database management system developed by Microsoft. It helps store, retrieve, and manage large amounts of structured data. Businesses use it to handle applications like websites, banking systems, and internal tools. It offers strong security, data recovery, and high performance.
- What are the different types of joins in SQL Server?
There are mainly four types of joins: INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN. INNER JOIN returns records that match in both tables. LEFT JOIN returns all records from the left table and matching ones from the right. RIGHT JOIN is the opposite. FULL JOIN returns all records when there is a match in either table.
- What is a primary key and a foreign key?
A primary key uniquely identifies each record in a table. It cannot be null or duplicate. A foreign key creates a relationship between two tables. It points to a primary key in another table, keeping the data consistent.
- How is a clustered index different from a non-clustered index?
A clustered index sorts and stores the data rows physically in order. Each table can have only one clustered index. A non-clustered index creates a separate structure to store pointers to the actual data. It allows faster searches without changing the physical order of the data.
- What is normalization? Why is it important?
Normalization organizes data to reduce redundancy and improve integrity. It breaks large tables into smaller related ones. It makes updates easier and avoids errors.
Note – Basic interview questions in SQL Server include topics like database structure, simple queries, indexing, backups, and user management.
Interview Questions on SQL Server for Freshers
Here is a list of commonly asked SQL Server fresher interview questions to help you prepare for your first job interview.
- What is a view in SQL Server?
A view is a virtual table based on a SQL query. It pulls data from one or more tables without storing it separately. Views help simplify complex queries, add security, and present data in a cleaner format.
- What is the difference between DELETE and TRUNCATE commands?
DELETE removes rows one at a time and logs each deletion. It can have a WHERE clause to delete specific records. TRUNCATE removes all rows quickly without logging individual row deletions. You cannot use a WHERE clause with TRUNCATE.
- How do you create a stored procedure in SQL Server?
To create a stored procedure, use the CREATE PROCEDURE statement followed by your SQL commands.
For example:
CREATE PROCEDURE GetEmployees AS SELECT * FROM Employees;
Stored procedures make it easier to reuse code and manage permissions.
- What is a trigger? Give an example.
A trigger is a special type of stored procedure that runs automatically after an event like INSERT, UPDATE, or DELETE.
Example:
CREATE TRIGGER AfterInsertEmployee ON Employees AFTER INSERT AS BEGIN PRINT ‘New employee added.’ END;
Triggers help maintain automatic actions inside the database.
- How can you retrieve unique records from a table?
You can use the DISTINCT keyword in a SELECT query.
Example:
SELECT DISTINCT Department FROM Employees;
This returns only unique department names without duplicates.
Also Read - Top 30+ PL/SQL Interview Questions and Answers
Interview Questions on SQL Server for Experienced Professionals
Let’s go through the important MS SQL Server interview questions that are often asked during interviews for experienced roles.
- How do you handle deadlocks in SQL Server?
Deadlocks happen when two processes block each other. To handle them, I identify the queries involved using SQL Server Profiler or Extended Events. Then, I optimize queries, add proper indexes, or change the transaction order. Sometimes, retry logic in the application also helps.
- What are common reasons for query performance issues?
Poor indexing, missing statistics, bad query design, too many joins, and blocking are major reasons. Large table scans, outdated execution plans, and locking problems can also slow down performance.
- Explain the concept of transaction isolation levels.
Transaction isolation levels control how data is accessed and locked during transactions.
- Read Uncommitted: Reads dirty data.
- Read Committed: Only reads committed data.
- Repeatable Read: Locks rows for the transaction duration.
- Serializable: Highest isolation, locks data range.
- Snapshot: Reads versioned data without blocking.
Each level balances between data accuracy and performance.
- How do you monitor database performance in SQL Server?
I use tools like Activity Monitor, SQL Server Profiler, and Extended Events. I check CPU usage, wait statistics, I/O bottlenecks, and slow-running queries. DMVs like sys.dm_exec_requests and sys.dm_exec_query_stats also help find problems early.
- What is the difference between a temp table and a table variable?
Temp tables are stored in tempdb and support indexes and transactions. They are better for handling large datasets. Table variables are stored in memory and work best with small datasets. Temp tables also offer better statistics for query optimization.
SQL Server Interview Questions for 3 Years Experienced
- What are aggregate functions in SQL Server?
- Can you describe a time when you optimized a SQL query?
- How do you approach debugging a stored procedure that is not returning expected results?
- What steps would you take if a database backup fails?
SQL Server Interview Questions for 5 Years Experienced
- What are common types of indexes used in SQL Server?
- Describe a project where you improved database performance.
- How do you handle urgent database downtime during peak hours?
- What are the key differences between a full backup and a differential backup?
SQL Server Interview Questions for 7 Years Experienced
- What is a common table expression (CTE) in SQL Server?
- Tell me about a time when you had to migrate a database to a new server.
- How do you prioritize tasks when handling multiple database issues at once?
- Explain how you would troubleshoot high CPU usage caused by SQL Server queries.
SQL Server Interview Questions for 8 Years Experienced
- What are the differences between OLTP and OLAP systems?
- Share an experience where you handled a critical database outage.
- How do you stay updated with changes in SQL Server technologies?
- How would you configure SQL Server Always On availability groups?
SQL Server Interview Questions for 10 Years Experienced
- What is partitioning in SQL Server and why is it used?
- Describe a situation where you led a team for a major database upgrade.
- How do you mentor junior DBAs in your team?
- How would you design a high-availability solution for a critical database?
Also Read - Top 25+ SQL DBA Interview Questions and Answers
Advanced SQL Server Interview Questions
These are advanced-level Microsoft SQL Server interview questions designed to test deep technical knowledge and problem-solving skills.
- What are the differences between a temp table, a table variable, and a common table expression?
Temp tables are physical tables stored in tempdb. They support indexes, constraints, and large datasets. Table variables are memory-based, faster for small data, but have limited statistics. A common table expression (CTE) is a temporary result set used mainly for simplifying complex queries.
- How does SQL Server handle concurrency and locking?
SQL Server uses locks to control how multiple users access the same data. It applies row-level, page-level, or table-level locks. Lock types like shared, exclusive, and update locks maintain data accuracy while allowing high concurrency.
- What is parameter sniffing and how do you resolve it?
Parameter sniffing happens when SQL Server creates an execution plan based on the first parameter value it sees. If later parameter values are different, the plan might not work well. You can resolve it by using OPTION (RECOMPILE), creating plan guides, or rewriting the query.
- How does SQL Server internally store indexes?
SQL Server stores indexes using a B-tree structure. Each node contains a key value and a pointer. Clustered indexes hold actual data rows at the leaf level. Non-clustered indexes store keys and pointers to the actual rows in the table.
- Explain the steps involved in database replication setup.
First, configure the distributor. Then set up the publisher, which sends data. Next, create the subscriber, which receives data. Finally, define articles, start the agents, and monitor replication using Replication Monitor.
Scenario-Based Interview Questions in SQL Server
Here are some SQL Server scenario-based interview questions to help you practice real-world problem-solving for your interviews.
- What would you do if a user complains about slow report generation?
First, I would check if the underlying queries are slow. I would review the execution plans, check for missing indexes, and confirm if too much data is being pulled. Sometimes optimizing the report design itself also helps.
- How would you recover a database that has gone into suspect mode?
I would first check the error logs to find the cause. Then, I would set the database to EMERGENCY mode, run DBCC CHECKDB to repair issues if possible, and finally bring the database back online after confirming data integrity.
- If a query is running fine today but slows down tomorrow, how would you troubleshoot it?
I would compare the execution plans from both days. Changes in statistics, parameter sniffing, blocking, or server resource issues are common reasons. Updating statistics or recompiling the query often solves the problem.
- What would you check if transaction log files are growing too large?
I would check if the database is in full recovery mode without regular log backups. I would also review long-running transactions and replication status if used. Regular log backups or shrinking logs after fixing issues can control file size.
- How would you move a large database from one server to another with minimum downtime?
I would take a full backup, restore it with NORECOVERY on the new server, and apply transaction log backups until the final cutover. This keeps downtime very low during migration.
SQL Server Practical Questions
We have also covered SQL Server practical questions to test your hands-on skills with real tasks you may face at work.
- Write a SQL query to find the second highest salary from an Employee table.
SELECT MAX(Salary)
FROM Employee
WHERE Salary < (SELECT MAX(Salary) FROM Employee);
- Write a query to update records in one table based on another table’s values.
UPDATE A
SET A.Salary = B.Salary
FROM Employee A
INNER JOIN SalaryUpdates B ON A.EmployeeID = B.EmployeeID;
- How would you create a new login and user in SQL Server?
First, I create a login at the server level:
CREATE LOGIN NewLogin WITH PASSWORD = ‘Password123!’;
Then, I create a user in the database and link it to the login:
CREATE USER NewUser FOR LOGIN NewLogin;
- Write a SQL query to detect duplicate rows in a table.
SELECT Name, COUNT(*)
FROM Employee
GROUP BY Name
HAVING COUNT(*) > 1;
- How would you create and schedule a backup job in SQL Server Agent?
First, open SQL Server Agent and create a new job. Add a job step with a BACKUP DATABASE command. Then create a schedule, set frequency and time, and attach it to the job. Finally, start the Agent service if it is not already running.
Also Read - Top 100 SQL Query Interview Questions and Answers
Other Important SQL Server Interview Questions
Here is a list of other important SQL Server interview questions that cover key topics often discussed during technical rounds.
SQL Server Integration Services Interview Questions
Here are some common SQL Server integration services interview questions.
- What is SSIS and when would you use it?
- How do you create a basic ETL package in SSIS?
- What is the difference between a Merge Join and a Lookup transformation in SSIS?
- How do you handle errors in SSIS packages?
- What are checkpoints in SSIS and how are they used?
SQL Server Reporting Services Interview Questions
- What is SSRS and how does it work with SQL Server?
- How do you create a report using SSRS?
- What is the difference between a matrix report and a tabular report in SSRS?
- How can you pass parameters into an SSRS report?
- How do you deploy SSRS reports to a server?
SQL Server Performance Tuning Interview Questions
- How do you identify slow-running queries in SQL Server?
- What are the most common causes of performance bottlenecks?
- How does indexing impact query performance?
- What are execution plans and how do you read them?
- How would you optimize SQL Server for faster read/write operations?
Always On SQL Server Interview Questions
Here are important interview questions on Always On in SQL Server to help you prepare for high availability and disaster recovery topics.
- What is Always On in SQL Server?
- What are the prerequisites for setting up Always On availability groups?
- What is the difference between a failover cluster and an availability group?
- How do you monitor Always On health status?
- What are automatic failover and manual failover in Always On?
SQL Server Replication Interview Questions
This is a list of commonly asked replication in SQL Server interview questions to help you understand key concepts and troubleshooting steps.
- What is replication in SQL Server and why is it used?
- What are the different types of replication available in SQL Server?
- How would you troubleshoot replication latency issues?
- What is a replication agent and what are its types?
- How do you reinitialize a subscription in replication?
Note – Interview questions on replication in SQL Server often include topics like types of replication, components, setup steps, and common issues.
SQL Server Architect Interview Questions
- How would you design a SQL Server architecture for a high-traffic e-commerce website?
- How do you decide when to scale vertically versus horizontally in SQL Server?
- What factors do you consider when designing a database for high availability and disaster recovery?
- How would you design a secure SQL Server environment?
- What role does cloud migration play in modern SQL Server architecture?
Also Read - Top 25+ Interview Questions For SSIS
How to Prepare for SQL Server Interview Questions
Preparing for a SQL Server interview needs focused study, hands-on practice, and clear understanding of core concepts.
- Revise basics like tables, keys, joins, indexes, transactions, and normalization.
- Practice writing SQL queries, stored procedures, and triggers.
- Understand backup strategies, replication, performance tuning, and security topics.
- Review common SQL Server interview questions and answers.
- Solve scenario-based questions and explain your thought process clearly.
- Set up a small test database to practice hands-on tasks.
- Read about recent SQL Server features and changes up to the latest version.
- Stay calm during interviews and always explain your answers step-by-step.
Wrapping Up
We hope these top 50+ SQL Server interview questions and answers help you feel more prepared. Practice regularly and stay updated with the latest SQL Server features.
Are you looking for SQL Server jobs? Visit Hirist, an online job portal for IT professionals, where you can easily find top SQL Server jobs in India.
FAQs
Is the SQL Server interview tough?
SQL Server interviews are manageable with the right preparation. If you understand basic concepts, performance tuning, and real-world scenarios, you can do well.
How to answer SQL Server questions in an interview?
When answering SQL Server questions, focus on explaining concepts in simple terms first. Then, support your answer with a real example or a quick scenario. Keep your explanation clear and structured. If the question is about performance, security, or troubleshooting, always mention best practices. If you are unsure about something, be honest and explain how you would approach solving it. Interviewers often look for your thinking process, not just textbook answers.
What are some commonly asked Infosys SQL Server interview questions and answers?
Infosys focuses on practical SQL Server skills during interviews. Here are commonly asked Infosys SQL Server interview questions.
- What is normalization? Explain its different forms with examples.
- How do you create and use stored procedures in SQL Server?
- What are different types of indexing techniques in SQL Server?
- How can you improve the performance of a SQL query?
- What is a transaction? Explain COMMIT, ROLLBACK, and SAVEPOINT in SQL Server.
What are common TCS SQL Server interview questions?
TCS often asks practical and real-world SQL Server questions during interviews. Here are common questions you should prepare for.
- What is the difference between a clustered and a non-clustered index in SQL Server?
- How would you optimize a slow-running SQL query?
- What are ACID properties in SQL Server, and why are they important?
- How do you handle deadlocks in a SQL Server database?
- What is the difference between DELETE, TRUNCATE, and DROP commands?
What is the average salary for a SQL Server Developer in India?
According to AmbitionBox, the SQL Server Developer salary in India ranges between ₹2 Lakhs to ₹9.5 Lakhs for professionals with 1 to 8 years of experience.
Which top companies are hiring for SQL Server roles in India?
Leading companies like TCS, Infosys, Wipro, Accenture, Cognizant, Capgemini, and HCL regularly hire SQL Server professionals across various levels.
How many rounds are there in a typical SQL Server interview?
Most companies conduct 2 to 4 rounds, including technical interviews, practical tests, and an HR discussion.
