52 Important SQL Server Interview Questions and Answers
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If you're applying for a position that works with SQL Servers, a hiring manager may ask you several questions about SQL Servers. They ask these questions to understand who you are as a person and whether you're a fit for the organisation. Understanding the questions they might ask can help you prepare for your interview. In this article, we discuss 52 SQL Server interview questions hiring managers may ask you.
General SQL server interview questions
A hiring manager can use general SQL server interview questions to learn more about you as a person. They can include questions about your background in SQL and questions about what you do outside of your profession. When you answer these questions, be honest about who you are and the things you enjoy. This can help you form personal connections with the hiring manager. Below are examples of general questions a hiring manager can ask you:
How did you become interested in SQL servers?
What do you enjoy doing outside of work?
Do you have any hobbies?
How do you balance your work and your personal life?
How do you handle stress?
What's your ideal work environment?
If you could recommend one change to your current manager, what would it be?
How would your best friend describe you?
How would your colleagues describe you?
What support do you want from your immediate manager?
Related: How to Prepare for an Interview
SQL Server interview questions about your background and experience
As an SQL Server professional, you may have a lot of background working with computers and database management systems. The hiring manager might be interested in learning about these backgrounds. These questions usually arise from your resume and can include questions about your education and specific skills. They may also ask about your qualifications. Below are examples of questions about your background and experiences with SQL Servers:
Why did you choose your major?
How did you learn about SQL Servers?
Why do you want to work for this organisation?
Where do you see yourself in one year?
What was your favourite class in school?
Tell me about your favourite project at school.
What extracurricular activities did you take part in?
How does your education relate to this role?
How many years of experience do you have with SQL Servers?
Where else did you apply for school? Did you receive other acceptance letters?
In-depth SQL Server interview questions
Hiring managers use in-depth interview questions to learn about your logical processes and how you solve challenges. They can involve both hypothetical questions related to the role you want and ways you overcame challenges in the past. Below are examples of in-depth SQL Server interview questions:
If a conflict arises with a colleague, how do you solve it?
Describe a time you made a mistake and how you addressed it.
Describe a time when your opinions and those of others were at odds.
If you lost a day's worth of work, what would you do?
Describe a challenging time you had at work and how you overcame it.
What is your greatest strength?
What's your greatest weakness?
Why should we hire you?
How do you plan for large projects?
Describe how you handle working on multiple projects simultaneously.
What are different locks in SQL Server?
What are constraints?
What is the purpose of the "FLOOR" function?
How many triggers are there? Please name them.
What is denormalisation?
What is the difference between the "TRUNCATE" and "DELETE" statements?
What's the difference between "UNION" and "UNIONALL"?
What's the difference between triggers and stored procedures?
What's the system function you can use to get the current user's user ID?
What's a self-join?
How do you trace the traffic hitting and SQL Server?
What happens at checkpoints?
Can you delete records from a view in SQL Server?
When should a developer use the "NOLOCK" hint? What can happen when you use it?
What is the purpose of "UPDATE STATISTICS"?
What steps would you take to improve the performance of a query that's performing poorly?
What is a prime attribute?
SQL Server interview questions with sample answers
Here is a list of interview questions and answers for SQL interview candidates:
1. What is normalisation and what is its purpose?
A hiring manager might ask you this question to learn about this specific process and whether you are familiar with clean and accurate data in SQL Server. When you answer this question, focus on providing a brief answer for what normalisation is. Then, explain why it's important in SQL Server.
Example: "Normalisation is organising data in tables so the results are unambiguous. It helps to reduce redundant data, which can slow down processes and make accessing data more difficult."
2. Define candidate key, alternate key and composite key.
When a hiring manager asks you to define terms, it's so they can understand how you interpret the systems you work with. For SQL Server, understanding not only the definitions of critical terms such as candidate key, alternate key and composite key but also how they are different and what they can do within the technology is helpful. As you answer this question, provide definitions for each key, then if you feel you need to describe more of their differences, elaborate on their definitions. This helps show a potential employer you are well-versed in SQL terminology and its practical applications.
Example: "A candidate key is one that can uniquely identify a row in a table. An alternate key is when a table has multiple candidate keys and one becomes the primary key, while the rest are alternate keys. A composite key is when multiple keys uniquely identify a row within a table."
3. What is the difference between global temporary tables and local temporary tables?
A hiring manager may use this question to test whether you understand the differences in terminology and their applications for users. When you answer this question, focus on defining both a global temporary table and a local temporary table, then explain how they can affect a user's experience. For example, a global temporary table is visible to all users while a local temporary table is visible to only one user.
Example: "A global temporary table is visible to all the users. SQL deletes these when the connection that created the table is closed. A local temporary table is visible when there's a connection and deletes when the connection is closed."
4. Can a SQL Server link to other servers?
For some positions that use SQL Server, you may also work with other types of servers. This is important for you to understand because connecting them has specific requirements. When a hiring manager asks you this question, they want to find out information about whether you know an SQL Server can connect to it and then what the requirements are. As you answer the question, know that the SQL Server can connect to other servers and then describe the specific conditions that the other server has to meet so a connection can form.
Example: "Yes, you can connect the SQL Server can to any other database that has an OLE-DB provider. This is a useful tool to have because it can help you find resources within external databases and use them instead of relying on your own data, making your SQL Server better."
5. What is an SQL Server agent?
A hiring manager can ask you this question to determine if you understand automated and scheduled tasks that SQL Server can perform. The system runs as a Windows service so that it can run the administrative tasks as the system starts or when you trigger them manually. As you answer this question, focus on what an SQL Server agent is, by definition and then describe how it helps you run programs automatically.
Example: "It's a component of Microsoft Windows that executes scheduled administrative tasks automatically on startup or when I trigger them manually."
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