Top 10 SQL Interview Questions and Answers

Data talks, and Structured Query Language (SQL) is the programming language that understands what it’s saying. SQL is used to manipulate and communicate with databases, allowing organizations to better access information. If you’re solid on SQL, you’ll be a highly desirable employee, as business analysts, software engineers, systems administrators, and data scientists all utilize the popular language. Once you’ve landed an interview, review these top 10 SQL interview questions and answers to get a leg up on the coding competition.

1. Tell me a little about yourself.

This open-ended question is many interviewers’ favorite way to kick off an interview. Get ahead of the competition by reading more about how to craft the perfect answer in our “Tell me about yourself” interview guide. Basically, the interviewer wants to get to know you—but they also want to know how you’ll create value for the business. Focus on relevant skills and accomplishments, and keep your response to a minute or less. Throwing in a memorable detail can help you make a lasting impression. Here’s a sample response to get you started:

“I got my degree in computer science, and I’ve been using it for the past two years as a database developer at my current company. I spend most of my time developing creating databases, optimizing network performance and security, and optimizing queries for use with other applications. Since I love problem-solving, I take an evaluative approach to solving issues, and I work through each process by trying out different solutions. Having minored in creative writing, I bring a unique skill set to my programming work. I have strong communication skills and the ability to write code, and then translate it into layman’s terms, so anyone can understand what I’m doing.”

2. What are your weaknesses?

For starters, don’t make a rookie mistake by saying that you have no weaknesses or that you “care too much about work.” Employers prefer authenticity over perfection, so choose weaknesses that aren’t true deficiencies and aren’t vital to the job at hand. You’re in SQL, so don’t say that you’re bad with numbers and can’t focus on the details. Be honest, and focus the majority of your response on what you’re doing to address your shortcomings and improve. You can read more about the greatness weakness questions here.

“At this point in my career, one of my biggest weaknesses is that I don’t have a lot of relevant work experience. I just graduated six months ago, and I’ve been job searching and taking coding courses that entire time. However, I’m a fast learner, and I’m highly adaptable, so I’m confident that I’ll build my skill set quickly once I start working full-time. I’m also coming to the workforce with a fresh perspective; I spend a lot of time reading about the latest industry trends. Additionally, I’ve struggled with being a little disorganized in the past, but I’ve found a great app that helps me stay on track with projects and deadlines.”

3. Do you work better on a team, with just one partner, or alone?

With this behavioral interview question, the interviewer is assessing your work style and personality to see how well you’ll mesh with their team and tasks. As a programmer, developer, or engineer, you’ll be spending a lot of time working solo. At the same time, you have to be able to partner with others to effectively and efficiently problem-solve. When you respond, assure your potential employer that you’re versatile. Share your honest preference, but then describe two positive examples: one in which you thrived as part of a team and one in which you thrived working solo.

“I’d say that I’m comfortable in all three types of environments, depending on the project at hand. Many days, I love to hunker down and work by myself, getting through complex coding needs without interruption. But I find it inspiring to work with and learn from others, so I’m happy to consult with colleagues to discuss the bigger picture. All in all, I enjoy collaborating with others and sharing ideas, but then I like being able to program independently.”

4. Where do you see yourself in five years?

Your new employer is going to invest a lot of time and money in your training and development, so they really want you to stick around. While you could be anywhere, a strong response to the five-year question will convey that you expect to be with this company and want to grow with them. Demonstrate your enthusiasm and ensure your response follows a natural career progression from the position you’re being interviewed for to future opportunities with the organization:

“I was originally drawn to this position and organization because there are ample opportunities to hone my SQL skill set and develop deep expertise in the years ahead. Once I’ve mastered the technical skills necessary to be a great SQL programmer, I hope to move into more development work. Five years from now, I’d love to be in a senior engineer role, taking on more leadership roles for projects. I’m also interested in the idea of potentially taking on more of a management role to help new hires succeed.”

5. Why should we hire you?

This question is your chance to sell yourself. Be sure to mention any special skills you have that would be valuable in the role, highlighting what differentiates you from other candidates. Be specific in your response, concisely summarizing your relevant strengths, qualifications, and achievements. Set yourself apart from the pack with an answer like this:

“Despite being an entry-level hire, I’ve proven myself in previous internships at high-profile companies and have a portfolio of successful projects. I started programming at a young age, and I regularly contribute to open-source coding projects, showing that I’m self-motivated and ambitious. Because I’ve been doing this for so long, across different industries and contexts, I have the knowledge to hit the ground running. I’ll be able to contribute from day one, bringing a unique perspective and unrivaled passion to the company.”

6. In your opinion, what are the standard SQL commands every SQL developer should know?

At some point in your interview, the interviewer will switch from general interview and fit questions to technical ones. This basic question tests your knowledge of the most essential commands necessary for programmers.

“Some of the standard commands every SQL developer should know include:

• SELECT – which allows you to select data from a database
• WHERE – which allows you to apply specific criteria to what you select
• ORDER – which is used to sort the results
• JOIN – which is used to join the related data that’s stored in one or more tables
• UNION – which allows you to append rows to each other.”

7. What is a Relational Database Management System (RDBMS), and which one are you most familiar with?

As most RDBMSs use SQL to access the database, knowledge of an RDBMS (or three) is crucial for a SQL professional. Employers will want to ensure they’re hiring a SQL developer who’s experienced with the particular set of web technologies that they use within their company, which is why it’s beneficial for you to have experience with multiple RDBMSs. Popular ones include MySQL, PostgreSQL, IBM DB 2, Microsoft Sccess, Oracle, and SQL Server.

“An RDBMS is a system that organizes data into tables, which are further organized into columns and rows. Columns represent properties and rows represent records. This relational model is an ideal way to sort through large volumes of data, as it can be queried in an almost unlimited number of ways. I have the most experience with Oracle, but I’m also familiar with Microsoft Access and Informix.”

8. What is a view and what are some advantages of it?

In our hyper-connected world, views are vital because they’re used to implement the security mechanism in the SQL server. The interviewer will want to ensure that you understand this vital concept. At the same time, this question confirms whether you understand when to use a view over a regular table. You might answer:

“A view is a virtual table that contains rows and columns. It’s similar to a real table, but it does not contain data of its own. Some advantages of views are that they take up no space, they can be used to restrict access to the database, and they offer a simple way to retrieve complicated query results that need to be executed frequently.”

9. Provide a sample of a correlated subquery.

As with any programming interview, you’re guaranteed to have multiple questions testing your coding abilities on the spot. While you may not be able to practice every potential coding scenario, being familiar with typical questions will help you prepare. You could provide something like:

SELECT employee_number, name
FROM employees AS emp
WHERE salary > (
SELECT AVG(salary)
FROM employees
WHERE department =
emp.department);

10. Name some commands that can be used to manipulate text in T-SQL code and explain what they do.

This is where having experience with multiple SQL extensions will come in handy. It’s likely that the interviewer will assess the versatility of your SQL programming knowledge. T-SQL (Transact-SQL) is an extension that adds additional features to the language. Some potential commands could be:

• REVERSE( character_expression )
• • Returns the reverse of a character expression
• REPLICATE( character_expression, integer_expression )
  • Repeats a character expression for a specified number of times
• CHARINDEX( findTextData, textData )
  • Returns the starting position of the specified expression in a character string
• LOWER ( character_expression )
  • Returns a character expression after converting uppercase character data to lowercase
• LEFT( character_expression, integer_expression )
  • Returns the left part of a character string with the specified number of characters

If you want to make it big as a programmer, the world of big data is a great place to start—and SQL is essential to kick-start your data-based career. Practice your coding, build your portfolio, and craft your own responses to these 10 SQL interview questions, and you’ll be set for interview success.