Mahedee Hasan

Mahedee Hasan

I am a Microsoft MVP (11th times), programmer, software developer, software architect, consultant, author, researcher, technical blogger, technical speaker, trainer and learner. I have more than 17 years experience in the field of software design and development.

100 MS SQL Server Interview Questions - Complete Guide for 2024

7 minute read

Preparing for a SQL Server interview can be challenging, especially with the vast array of topics that might be covered. Whether you’re a junior developer or a senior database professional, having a comprehensive list of potential questions is invaluable for interview preparation.

This guide presents 100 carefully curated MS SQL Server interview questions organized by difficulty level, covering everything from basic syntax to advanced performance optimization techniques.

Table of Contents

Beginner/Junior Level Questions (1-50)

Basic SQL Server Fundamentals

1. What is SQL Server and what are its main components?

2. What is the difference between SQL and T-SQL?

3. What are the different editions of SQL Server?

4. What is a database schema in SQL Server?

5. What is the difference between a database and a table?

Data Types and Tables

6. What is the difference between “char” and “varchar”?

7. What is the difference between varchar and text in SQL Server?

8. What is the difference between NVARCHAR and VARCHAR in SQL Server?

9. Write syntax to create a table.

10. How do you add a column to an existing table?

Basic Queries and Operations

11. What is the difference between Delete and Truncate in SQL Server?

12. How do you select all records from a table?

13. How to select top 10 employees from employee table?

14. How does the “distinct” keyword work?

15. Why is the “Where” clause needed?

Joins

16. How does inner join work? Give an example.

17. How does left outer join work?

18. How does right outer join work? Give an example.

19. How does full outer join work? Give an example?

20. How does Cross Join work? Give an example?

21. What is self joining? Explain with an example?

22. Which one is faster – Inner join or Cross Join?

Functions and Aggregation

23. How does “group by” clause work?

24. How does “having” clause work?

25. Find out the maximum salary from a salary table?

26. How do you find number of employees from employee table?

27. How do “between” and “in” operators work?

Stored Procedures and Functions

28. What is a stored procedure in SQL Server, and why would you use it?

29. How do you create a stored procedure in SQL Server?

30. How do you execute a stored procedure in SQL Server?

31. What is function in SQL Server? How many types of functions?

32. How is a parameter passed to SQL function and how do you call a function?

33. What is the difference between Stored Procedure and Function in SQL Server?

Views and Basic Database Objects

34. What is a view? What is the difference between table and view?

35. How do you create a view in SQL Server?

36. What are the advantages of using views?

Constraints

37. What is constraint? Tell different types of constraint and their functionality.

38. How do primary key constraints work?

39. How do foreign key constraints work?

40. How do not null constraints, check constraints, and unique constraints work?

Basic Transactions

41. What is commit and rollback? How do they work?

42. What do you know about transaction block? How does it work?

43. How to handle transaction in SQL Server? Explain with an example.

Basic SQL Operations

44. What are DDL and DML? Give examples.

45. How do you move all data to another table using a query?

46. What do you know about SQL wildcards? Give examples.

47. Union / Union all, requirement and difference.

48. What is a sub query? Give an example.

49. Write a query to select the third employee based on salary.

50. How do you update multiple records in a table?

Advanced/Senior Level Questions (51-100)

Advanced Indexing and Performance

51. What is Clustered index and Non-clustered index in SQL Server? How do they work?

52. What are covering indexes? Explain with example.

53. What is the difference between clustered and non-clustered indexes in terms of performance?

54. How do you identify missing indexes in SQL Server?

55. What is index fragmentation and how do you handle it?

Performance Optimization

56. What will you do to optimize a stored procedure in SQL Server?

57. Suppose you are writing a complex query joining six or seven tables, which techniques will you follow to optimize query performance?

58. What can you do for performance optimization in SQL Server?

59. How do you use SQL Server Profiler for performance tuning?

60. What is execution plan and how do you analyze it?

Advanced Stored Procedures and Functions

61. What is a parameterized stored procedure, and why would you use it?

62. How do you modify a stored procedure in SQL Server?

63. What is input and output parameter in stored procedure? How do they work?

64. How do you handle errors in stored procedures?

65. What are table-valued functions and how are they different from scalar functions?

Advanced Transactions and Concurrency

66. What are isolation levels in SQL Server?

67. What is deadlock and how do you handle it?

68. Explain ACID properties in database transactions.

69. What is the difference between pessimistic and optimistic locking?

70. How do you implement row-level locking in SQL Server?

Temporary Tables and Table Variables

71. What is the difference between temporary tables and table variables?

72. Explain with a real world use case for global temp table.

73. When would you use a CTE (Common Table Expression) vs a temporary table?

74. What are the performance implications of using temporary tables?

Advanced Joins and Complex Queries

75. Discuss different types of joining using examples in SQL Server.

76. How do you write a recursive query using CTE?

77. What is the difference between APPLY and JOIN operators?

78. How do you handle many-to-many relationships in SQL queries?

Advanced Data Types and Features

79. What are window functions in SQL Server?

80. How do you work with XML data in SQL Server?

81. What are computed columns and when would you use them?

82. How do you handle large object (LOB) data types?

Security and Permissions

83. How do you implement security in SQL Server?

84. What is the difference between authentication and authorization?

85. How do you encrypt sensitive data in SQL Server?

86. What are database roles and how do you manage them?

Backup, Recovery, and Maintenance

87. What are the different types of backups in SQL Server?

88. How do you implement point-in-time recovery?

89. What is log shipping and how does it work?

90. How do you automate database maintenance tasks?

Cloud and Advanced Topics

91. What is the difference between Microsoft SQL Server and SQL Server in Azure?

92. How do you migrate from on-premises SQL Server to Azure?

93. What are the benefits of using SQL Server Always On Availability Groups?

94. How do you monitor SQL Server performance in a cloud environment?

Complex Scenarios and Problem Solving

95. You have a table named “Employee” with columns: ID, Name, Salary, DepartmentID. Write queries to find the highest paid employee in each department.

96. How would you design a database for an e-commerce application?

97. How do you handle data archiving in large databases?

98. What strategies would you use for partitioning large tables?

99. How do you troubleshoot slow-performing queries?

100. Explain a complex database problem you’ve solved and your approach to solving it.

Interview Preparation Tips

For Beginner/Junior Positions:

  • Focus on fundamental SQL syntax and basic operations
  • Understand different types of joins with practical examples
  • Practice writing basic stored procedures and functions
  • Know the difference between various data types
  • Understand basic database design principles

For Advanced/Senior Positions:

  • Deep dive into performance tuning and optimization techniques
  • Understand indexing strategies and when to use them
  • Know advanced T-SQL features like window functions, CTEs
  • Be familiar with SQL Server administration tasks
  • Understand cloud migration and Azure SQL Database

General Preparation Strategy:

  • Practice writing queries on sample databases (Northwind, AdventureWorks)
  • Understand the business context behind technical decisions
  • Be prepared to explain your thinking process
  • Practice optimizing poorly performing queries
  • Stay updated with latest SQL Server features and best practices

Common Interview Formats:

  • Technical Questions: Direct questions about SQL concepts
  • Coding Challenges: Writing queries to solve specific problems
  • Scenario-Based: Real-world problems requiring database solutions
  • Performance Optimization: Analyzing and improving existing queries

Conclusion

This comprehensive list of 100 SQL Server interview questions covers the breadth of knowledge expected at different career levels. Remember that interviews are not just about knowing the right answers, but also about demonstrating your problem-solving approach and ability to explain complex concepts clearly.

The key to success is not memorizing answers but understanding the underlying concepts and being able to apply them to real-world scenarios. Practice regularly with sample databases, stay updated with the latest SQL Server features, and always be prepared to explain your reasoning.

Whether you’re preparing for your first database role or advancing to a senior position, these questions will help you assess your knowledge gaps and focus your preparation efforts effectively.

Good luck with your SQL Server interviews!

Have questions about any of these topics? Feel free to reach out in the comments below. Happy learning!

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