Advanced SQL interview question to hire experienced candidates

Advanced SQL interview question to hire experienced candidates

RahulApril 26th, 20214 min read

We now live in an era where data is the most important resource. It is consumed and leveraged at its best by businesses of all sizes and types. In fact, data has become one of the most crucial and essential elements of a business’s decision-making process.

As SQL has evolved into the standardized interface for data processing, so has the market for SQL-savvy developers. According to Tableplus, there are over 1.4 million developer positions available, with about 1 million of them employing SQL developers or requiring SQL as a necessary ability.

If you’re an HR who is looking to hire a SQL developer and you don’t where to begin, don’t worry! This article will help you understand the requirements you must have a look at to interview SQL developers. Besides, we will walk you through different SQL interview questions you should ask and how online code editors can help you assess the skill level of the applicants.

Required skillset for an experienced SQL Developer

SQL is a programming language used to store, manipulate, and retrieve data from relational databases. It is the standard database language used by all relational database systems, including MySQL, Oracle, MSSQL, Informix, Sybase, SQL Server, and PostgreSQL. Moreover, you can call it a database's equivalent of a server-side script that is in control of:

  • Data retrieval
  • Data editing: updating, inserting, creating new records, and deleting
  • Generating views, and
  • Generating new databases

For SQL developers, having strong technical knowledge in set theory is important. If they lack this expertise, they would require extracting individual data from different resources. This, in turn, can be an obstacle for bulk data processing and even time-consuming.

If you're trying to recruit a SQL developer but aren't sure how to do so, or what to look for in an applicant, a guide like this will definitely be of help to you.

Start with evaluating candidates with SQL Online Tests

Before bringing in the candidates for the interview, make sure to assess the candidates with online python coding test. These skill tests will help you to determine the top one percent of python developers among the ones you were successful in attracting.

As an employer, you can easily evaluate candidate’s knowledge on various concepts, frameworks, and coding with this advanced SQL coding test for experienced.

These simulation-based SQL technical assessments prove to be the most reliable way of testing candidate’s python programming skills. Evaluate the knowledge of candidates and coding style with the assessments that are created by a team of Subject Matter Experts. These tests give balanced emphasis to both theory and coding questions.

Advanced SQL Interview Questions You Must Ask To Hire Experienced Candidates

While you sit to interview an applicant for the SQL position in your organization, it is necessary to have a list of SQL interview questions prepared. And, to help you choose the best candidate, here’s the list.

  1. Demonstrate various Joins?
  2. Explain cursor and give demonstration?
  3. Create a view using the above tables?
  4. What is the ACID property in a database?
  5. Give an example of a stored procedure.
  6. What do you understand by normalization and denormalization?
  7. What is wrong with the below-given SQL query?

    SELECT gender, AVG(age) FROM employee WHERE AVG(age)>30 GROUP BY gender
  8. Create an auto increment function that increments salary by $1000 when age of the team member increases?
  9. What are the various SQL subsets?
  10. Create a error trigger if mismatched ID is used? Rectify if necessary.
  11. What is the total salary paid?
  12. What is the distinction between the SQL data types CHAR and VARCHAR2?
  13. What do you understand by a temporary table? Write a query to create a temporary table.
  14. What Are Constraints and How Do They Affect You?
  15. Define a unique key.

These are some of the important questions you can ask. But before that make sure you research their answers and get a better understanding of the subject.

Things To Consider Before Finalizing SQL Developers

Depending on the level or position you’re filling the requirements for, the applicant’s skills may vary. So, take a look below to determine who is the right fit for your organizational role.

For Beginners

VARCHAR, CHARACTER, ARRAY, BOOLEAN, DECIMAL, and other data types ought to be familiar to a beginner SQL developer. They also should be familiar with Choose, SUM, COUNT, DISTINCT, MAX/MIN, and GROUP BY functions.

For Intermediates

Intermediate SQL programmers should be familiar with all SQL data types as well as certain more advanced features. They must be familiar with features such as JOINS, EXISTS, NULL, and HANDLING.

For Seniors

An experienced SQL developer must be familiar with all the above functions in addition to data pivots, functions, errors, and triggers like COMMIT ROLLBACK.

Why You Must Use Online Coding Platforms?

The best way to measure database skills is to have the candidate take an online SQL skill exam on an online coding sandbox. It enables professional and non-technical recruiters and recruiting managers to perform a pre-hire evaluation of candidates and pick out the right candidates within a relatively short time, minimizing time-to-hire by up to 50%.

Here are some other benefits:

  • HRs and recruiting managers will now invest more time reviewing proficient applicants by removing unqualified applicants before the first face-to-face interview with the aid of online SQL tests.
  • The SQL skills test will help you recruit work-seekers quicker by reducing time-to-hire by up to 50%.
  • The assessments are a great mix of theory and practice questions that assess an applicant's understanding of SQL concepts and coding.
  • HRs and recruiters can make smarter hiring decisions with the help of a collection of integrated data, recruiting analytics, and analyses.
Final Word

With these tips in mind, you are bound to be ready to take an interview. But make sure you remember every point mentioned in this article like questions, making use of live interview tools, and being prepared with SQL interview questions. Get set and rolling for your next SQL interview!

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