Home
/
Blog
/
Developer Insights
/
Hiring DEV Talent: SQL Interview Questions

Hiring DEV Talent: SQL Interview Questions

Author
Sonaksh Singh
Calendar Icon
June 23, 2022
Timer Icon
5 min read
Share

With SQL taking its place among the most popular developing languages for the management of data, as per this 2021 report by Statista, SQL is pretty much the most popular language, and hiring developers for the same is a smart move to make. This is why it is quite important for companies to take interest in it and to further make use of it

Organizations can use this language for data analysis, management, and much more. This is exactly why you want to make sure you find the right SQL coding developer for your organization.

Technical recruitment can be quite challenging but there are things you can do apart from just asking the same old questions for an effective interview process. Hiring developer needn’t be difficult at all, want to know how? Keep on reading

How Technical Recruiters Can Step Up Their Game

Given how the landscape of technical recruitment looks right now, especially post pandemic, it is imperative that recruiters level up their game.

Asking the same old SQL interview questions will not work as great as before, as a recruiter apart from looking for developers, you must also look for ways to render your recruitment game much more efficient. From learning new skills to being more inclusive in your approach, there are a ton of things you can do to keep pace with the ever-growing world of tech recruitment.

Set Clear Expectations

Setting clear expectations is something that should be among the top priorities in your recruitment process.

You can only assess the candidate thoroughly when the candidate understands what is expected of him/her. During the very first interview process, setting clear objectives is important. This also means that you will be offering your candidates a realistic preview of the job.

When you talk about objectives and expectations, you should get the candidate excited about the role. With clear objectives in mind, it will be easier for the candidate to understand what they must do to secure their position and they will also know what to expect from the job as well.

Use Real-World Problems

Hiring a skilled developer sounds good but know that just developing skills aren’t enough. Having adept problem-solving skills can go a long way, it can also improve their developing skills. Problem-solving is an indicator of a great employee.

To assess their problem-solving skills, you ought to use real-world problems. Using real-world scenarios will also give you a good idea about their skills, being able to solve real-world problems also showcases:

  • Adaptability
  • Creative thinking
  • Analytical thinking

So by bringing this method to the table, you are not only hiring developers who know the language, but you are also hiring someone who will take initiative and try to bring out the best in themselves.

Look Beyond Technical Skills

As a follow-up to the point above, looking beyond technical skills and problem-solving skills definitely pays off.

It doesn’t matter how good the candidate is unless he is the right fit for the organization. You need to look for open-minded individuals who can be great team players as well. You need people who will stick around for a long period of time, someone who is befitting to the work environment the organization has to offer.

Use Tools

There are several platforms for hiring developers that take the process of screening and interviewing to a whole new level.

Gone are the days where you had to take an interview and then ask the candidate to write a code on paper. With interview and screening tools, you can request the candidate to work on a code right then and there, after which you can use assessment tools to give your candidate feedback immediately.

Also Read: 6 things to look for in your coding assessment tool

Online Tech Forums and Communities

Online Tech Forums and Communities is one of the best places to find developers. This concept is relatively new, but engaging with developers and coders through these forums will give you several options and also this is a way of sourcing candidates even before a job vacancy pops up.

SQL skills required for developers

SQL, or Structured Query Language, is the backbone of many modern data operations. But when hiring SQL developers, it’s essential to remember that you’re not just looking for someone who knows how to write a query. You’re searching for a multifaceted individual with a blend of technical knowledge and other attributes that make them an invaluable asset.

Here are the skills to look for:

Strong foundation in SQL: At its core, an SQL developer should possess a robust understanding of SQL syntax and structures. This includes crafting complex queries, understanding JOIN operations, and implementing sub-queries and triggers.

Database design and normalization: Proficiency in designing databases is crucial. A skilled developer should understand normalization principles to ensure data integrity and efficiency.

Knowledge of RDBMS: Familiarity with popular Relational Database Management Systems, like MySQL, PostgreSQL, Oracle, or SQL Server, is essential. Each system has its nuances, so knowledge of your specific platform is a plus.

Performance tuning: Writing an SQL query is one thing; optimizing it for performance is another. Candidates should know how to analyze query performance and make necessary adjustments.

Understanding of indexing: Knowing how and when to use indexes to optimize queries is a hallmark of an experienced SQL developer.

Stored procedures and functions: The ability to create and modify stored procedures and functions allows for more complex operations and can help with performance.

Integration skills: Often, SQL databases don’t stand alone. Your developer might need to integrate them with other systems, so familiarity with integration tools and methodologies is a plus.

Backup and recovery: An understanding of backup techniques, and secure methods, such as air gap backups,, as well as the ability to restore data in case of failures, is crucial.

ETL processes: For businesses that rely on data warehousing, knowledge of ETL (Extract, Transform, Load) processes can be invaluable.

Soft skills: Beyond the technical, effective communication is vital. SQL developers often need to collaborate with other teams, gather requirements, and sometimes explain complex data concepts in layman’s terms.

Problem-solving and analytical thinking: Databases often present intricate challenges. A sharp analytical mind, combined with a problem-solving attitude, can set a great SQL developer apart.

The tech world evolves rapidly. Along with these skills, a top SQL developer should also demonstrate a commitment to continuous learning, staying updated with the latest in database technologies and best practices. With increasing concerns about data breaches, an understanding of security protocols and best practices is also crucial.

Sample SQL Interview Questions

Here are a few sample questions you can refer to:

  1. List out the standard SQL commands.
  2. Explain the different subsets of SQL
  3. Explain what Relational Database Management Is
  4. List out the differences between outer join and inner join
  5. How does data normalization work and what is its purpose?
  6. What Is Union?
  7. What is a UNIQUE constraint? Explain.
  8. How do you copy one table to another?
  9. How do you insert a row for identity column implicity?
  10. Explain the difference between multiple-row functions and single-row functions
  11. What would be the output of the below-mentioned query of an employee table with 10 records?
  1. What is an execution plan? How do you view it and use it?
  2. Given below is customer table with data for which you must write one SQL statement link and sequence customer names in the following single semicolon-separated string

Sebastian V; Akshay Varma; Manoj Kumar; Shrishti Singh; Abhay

  1. Explain the difference between varchar2 and char?
  2. What is the NVL function in SQL? How is it different from NVL2?
  3. Give the SQL statement for the below
  4. In the below mentioned table

Write a query to list out people who attended class more than once in a single day. Let the order start from the most recent and group it by the user and lesson attended.

These are some of the questions you can ask when you’re in the process of interviewing and a hiring developer, but remember that a well-planned recruitment strategy always pays off in a great manner.

Moreover, technology has the answer for all the above, there are multiple tools available through which you can elevate your recruitment strategy. Like HackerEarth’s live interview tool which allows real-time code editing, similarly, there are other tools.

So don’t wait too long to make your recruitment game strong.

Subscribe to The HackerEarth Blog

Get expert tips, hacks, and how-tos from the world of tech recruiting to stay on top of your hiring!

Author
Sonaksh Singh
Calendar Icon
June 23, 2022
Timer Icon
5 min read
Share

Hire top tech talent with our recruitment platform

Access Free Demo
Related reads

Discover more articles

Gain insights to optimize your developer recruitment process.

Vibe Coding: Shaping the Future of Software

A New Era of CodeVibe coding is a new method of using natural language prompts and AI tools to generate code. I have seen firsthand that this change makes software more accessible to everyone. In the past, being able to produce functional code was a strong advantage for developers. Today,...

A New Era of Code

Vibe coding is a new method of using natural language prompts and AI tools to generate code. I have seen firsthand that this change makes software more accessible to everyone. In the past, being able to produce functional code was a strong advantage for developers. Today, when code is produced quickly through AI, the true value lies in designing, refining, and optimizing systems. Our role now goes beyond writing code; we must also ensure that our systems remain efficient and reliable.

From Machine Language to Natural Language

I recall the early days when every line of code was written manually. We progressed from machine language to high-level programming, and now we are beginning to interact with our tools using natural language. This development does not only increase speed but also changes how we approach problem solving. Product managers can now create working demos in hours instead of weeks, and founders have a clearer way of pitching their ideas with functional prototypes. It is important for us to rethink our role as developers and focus on architecture and system design rather than simply on typing code.

The Promise and the Pitfalls

I have experienced both sides of vibe coding. In cases where the goal was to build a quick prototype or a simple internal tool, AI-generated code provided impressive results. Teams have been able to test new ideas and validate concepts much faster. However, when it comes to more complex systems that require careful planning and attention to detail, the output from AI can be problematic. I have seen situations where AI produces large volumes of code that become difficult to manage without significant human intervention.

AI-powered coding tools like GitHub Copilot and AWS’s Q Developer have demonstrated significant productivity gains. For instance, at the National Australia Bank, it’s reported that half of the production code is generated by Q Developer, allowing developers to focus on higher-level problem-solving . Similarly, platforms like Lovable enable non-coders to build viable tech businesses using natural language prompts, contributing to a shift where AI-generated code reduces the need for large engineering teams. However, there are challenges. AI-generated code can sometimes be verbose or lack the architectural discipline required for complex systems. While AI can rapidly produce prototypes or simple utilities, building large-scale systems still necessitates experienced engineers to refine and optimize the code.​

The Economic Impact

The democratization of code generation is altering the economic landscape of software development. As AI tools become more prevalent, the value of average coding skills may diminish, potentially affecting salaries for entry-level positions. Conversely, developers who excel in system design, architecture, and optimization are likely to see increased demand and compensation.​
Seizing the Opportunity

Vibe coding is most beneficial in areas such as rapid prototyping and building simple applications or internal tools. It frees up valuable time that we can then invest in higher-level tasks such as system architecture, security, and user experience. When used in the right context, AI becomes a helpful partner that accelerates the development process without replacing the need for skilled engineers.

This is revolutionizing our craft, much like the shift from machine language to assembly to high-level languages did in the past. AI can churn out code at lightning speed, but remember, “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” Use AI for rapid prototyping, but it’s your expertise that transforms raw output into robust, scalable software. By honing our skills in design and architecture, we ensure our work remains impactful and enduring. Let’s continue to learn, adapt, and build software that stands the test of time.​

Ready to streamline your recruitment process? Get a free demo to explore cutting-edge solutions and resources for your hiring needs.

Guide to Conducting Successful System Design Interviews in 2025

What is Systems Design?Systems Design is an all encompassing term which encapsulates both frontend and backend components harmonized to define the overall architecture of a product.Designing robust and scalable systems requires a deep understanding of application, architecture and their underlying components like networks, data, interfaces and modules.Systems Design, in its...

What is Systems Design?

Systems Design is an all encompassing term which encapsulates both frontend and backend components harmonized to define the overall architecture of a product.

Designing robust and scalable systems requires a deep understanding of application, architecture and their underlying components like networks, data, interfaces and modules.

Systems Design, in its essence, is a blueprint of how software and applications should work to meet specific goals. The multi-dimensional nature of this discipline makes it open-ended – as there is no single one-size-fits-all solution to a system design problem.

What is a System Design Interview?

Conducting a System Design interview requires recruiters to take an unconventional approach and look beyond right or wrong answers. Recruiters should aim for evaluating a candidate’s ‘systemic thinking’ skills across three key aspects:

How they navigate technical complexity and navigate uncertainty
How they meet expectations of scale, security and speed
How they focus on the bigger picture without losing sight of details

This assessment of the end-to-end thought process and a holistic approach to problem-solving is what the interview should focus on.

What are some common topics for a System Design Interview

System design interview questions are free-form and exploratory in nature where there is no right or best answer to a specific problem statement. Here are some common questions:

How would you approach the design of a social media app or video app?

What are some ways to design a search engine or a ticketing system?

How would you design an API for a payment gateway?

What are some trade-offs and constraints you will consider while designing systems?

What is your rationale for taking a particular approach to problem solving?

Usually, interviewers base the questions depending on the organization, its goals, key competitors and a candidate’s experience level.

For senior roles, the questions tend to focus on assessing the computational thinking, decision making and reasoning ability of a candidate. For entry level job interviews, the questions are designed to test the hard skills required for building a system architecture.

The Difference between a System Design Interview and a Coding Interview

If a coding interview is like a map that takes you from point A to Z – a systems design interview is like a compass which gives you a sense of the right direction.

Here are three key difference between the two:

Coding challenges follow a linear interviewing experience i.e. candidates are given a problem and interaction with recruiters is limited. System design interviews are more lateral and conversational, requiring active participation from interviewers.

Coding interviews or challenges focus on evaluating the technical acumen of a candidate whereas systems design interviews are oriented to assess problem solving and interpersonal skills.

Coding interviews are based on a right/wrong approach with ideal answers to problem statements while a systems design interview focuses on assessing the thought process and the ability to reason from first principles.

How to Conduct an Effective System Design Interview

One common mistake recruiters make is that they approach a system design interview with the expectations and preparation of a typical coding interview.
Here is a four step framework technical recruiters can follow to ensure a seamless and productive interview experience:

Step 1: Understand the subject at hand

  • Develop an understanding of basics of system design and architecture
  • Familiarize yourself with commonly asked systems design interview questions
  • Read about system design case studies for popular applications
  • Structure the questions and problems by increasing magnitude of difficulty

Step 2: Prepare for the interview

  • Plan the extent of the topics and scope of discussion in advance
  • Clearly define the evaluation criteria and communicate expectations
  • Quantify constraints, inputs, boundaries and assumptions
  • Establish the broader context and a detailed scope of the exercise

Step 3: Stay actively involved

  • Ask follow-up questions to challenge a solution
  • Probe candidates to gauge real-time logical reasoning skills
  • Make it a conversation and take notes of important pointers and outcomes
  • Guide candidates with hints and suggestions to steer them in the right direction

Step 4: Be a collaborator

  • Encourage candidates to explore and consider alternative solutions
  • Work with the candidate to drill the problem into smaller tasks
  • Provide context and supporting details to help candidates stay on track
  • Ask follow-up questions to learn about the candidate’s experience

Technical recruiters and hiring managers should aim for providing an environment of positive reinforcement, actionable feedback and encouragement to candidates.

Evaluation Rubric for Candidates

Facilitate Successful System Design Interview Experiences with FaceCode

FaceCode, HackerEarth’s intuitive and secure platform, empowers recruiters to conduct system design interviews in a live coding environment with HD video chat.

FaceCode comes with an interactive diagram board which makes it easier for interviewers to assess the design thinking skills and conduct communication assessments using a built-in library of diagram based questions.

With FaceCode, you can combine your feedback points with AI-powered insights to generate accurate, data-driven assessment reports in a breeze. Plus, you can access interview recordings and transcripts anytime to recall and trace back the interview experience.

Learn how FaceCode can help you conduct system design interviews and boost your hiring efficiency.

How Candidates Use Technology to Cheat in Online Technical Assessments

Impact of Online Assessments in Technical Hiring In a digitally-native hiring landscape, online assessments have proven to be both a boon and a bane for recruiters and employers. The ease and...

Impact of Online Assessments in Technical Hiring


In a digitally-native hiring landscape, online assessments have proven to be both a boon and a bane for recruiters and employers.

The ease and efficiency of virtual interviews, take home programming tests and remote coding challenges is transformative. Around 82% of companies use pre-employment assessments as reliable indicators of a candidate's skills and potential.

Online skill assessment tests have been proven to streamline technical hiring and enable recruiters to significantly reduce the time and cost to identify and hire top talent.

In the realm of online assessments, remote assessments have transformed the hiring landscape, boosting the speed and efficiency of screening and evaluating talent. On the flip side, candidates have learned how to use creative methods and AI tools to cheat in tests.

As it turns out, technology that makes hiring easier for recruiters and managers - is also their Achilles' heel.

Cheating in Online Assessments is a High Stakes Problem



With the proliferation of AI in recruitment, the conversation around cheating has come to the forefront, putting recruiters and hiring managers in a bit of a flux.



According to research, nearly 30 to 50 percent of candidates cheat in online assessments for entry level jobs. Even 10% of senior candidates have been reportedly caught cheating.

The problem becomes twofold - if finding the right talent can be a competitive advantage, the consequences of hiring the wrong one can be equally damaging and counter-productive.

As per Forbes, a wrong hire can cost a company around 30% of an employee's salary - not to mention, loss of precious productive hours and morale disruption.

The question that arises is - "Can organizations continue to leverage AI-driven tools for online assessments without compromising on the integrity of their hiring process? "

This article will discuss the common methods candidates use to outsmart online assessments. We will also dive deep into actionable steps that you can take to prevent cheating while delivering a positive candidate experience.

Common Cheating Tactics and How You Can Combat Them


  1. Using ChatGPT and other AI tools to write code

    Copy-pasting code using AI-based platforms and online code generators is one of common cheat codes in candidates' books. For tackling technical assessments, candidates conveniently use readily available tools like ChatGPT and GitHub. Using these tools, candidates can easily generate solutions to solve common programming challenges such as:
    • Debugging code
    • Optimizing existing code
    • Writing problem-specific code from scratch
    Ways to prevent it
    • Enable full-screen mode
    • Disable copy-and-paste functionality
    • Restrict tab switching outside of code editors
    • Use AI to detect code that has been copied and pasted
  2. Enlist external help to complete the assessment


    Candidates often seek out someone else to take the assessment on their behalf. In many cases, they also use screen sharing and remote collaboration tools for real-time assistance.

    In extreme cases, some candidates might have an off-camera individual present in the same environment for help.

    Ways to prevent it
    • Verify a candidate using video authentication
    • Restrict test access from specific IP addresses
    • Use online proctoring by taking snapshots of the candidate periodically
    • Use a 360 degree environment scan to ensure no unauthorized individual is present
  3. Using multiple devices at the same time


    Candidates attempting to cheat often rely on secondary devices such as a computer, tablet, notebook or a mobile phone hidden from the line of sight of their webcam.

    By using multiple devices, candidates can look up information, search for solutions or simply augment their answers.

    Ways to prevent it
    • Track mouse exit count to detect irregularities
    • Detect when a new device or peripheral is connected
    • Use network monitoring and scanning to detect any smart devices in proximity
    • Conduct a virtual whiteboard interview to monitor movements and gestures
  4. Using remote desktop software and virtual machines


    Tech-savvy candidates go to great lengths to cheat. Using virtual machines, candidates can search for answers using a secondary OS while their primary OS is being monitored.

    Remote desktop software is another cheating technique which lets candidates give access to a third-person, allowing them to control their device.

    With remote desktops, candidates can screen share the test window and use external help.

    Ways to prevent it
    • Restrict access to virtual machines
    • AI-based proctoring for identifying malicious keystrokes
    • Use smart browsers to block candidates from using VMs

Future-proof Your Online Assessments With HackerEarth

HackerEarth's AI-powered online proctoring solution is a tested and proven way to outsmart cheating and take preventive measures at the right stage. With HackerEarth's Smart Browser, recruiters can mitigate the threat of cheating and ensure their online assessments are accurate and trustworthy.
  • Secure, sealed-off testing environment
  • AI-enabled live test monitoring
  • Enterprise-grade, industry leading compliance
  • Built-in features to track, detect and flag cheating attempts
Boost your hiring efficiency and conduct reliable online assessments confidently with HackerEarth's revolutionary Smart Browser.
Top Products

Explore HackerEarth’s top products for Hiring & Innovation

Discover powerful tools designed to streamline hiring, assess talent efficiently, and run seamless hackathons. Explore HackerEarth’s top products that help businesses innovate and grow.
Frame
Hackathons
Engage global developers through innovation
Arrow
Frame 2
Assessments
AI-driven advanced coding assessments
Arrow
Frame 3
FaceCode
Real-time code editor for effective coding interviews
Arrow
Frame 4
L & D
Tailored learning paths for continuous assessments
Arrow
Get A Free Demo