This comprehensive guide will walk you through the top questions for a variety of data positions and provide you with advice on how to prepare for your upcoming SQL interview.
An essential tool for any aspiring data scientist is SQL. This article offers a roadmap for learning SQL, getting ready for it, and nailing your next SQL interview for a Data Science position. We will first discuss the reasons why SQL is so popular before breaking down the SQL skills required for each role, such as data analyst, data scientist, machine learning engineer, etc. Additionally, we give you practical interview examples from the StrataScratch Platform that highlight some of these abilities as well as a step-by-step learning manual for mastering SQL, even if you are not too familiar with SQL concepts, so you can land your dream job.
So let’s begin by discussing why SQL is so popular in the world of data science.
The tabular data storage format is one of the main factors in SQL’s popularity. Databases can be easily pictured as massive spreadsheets with countless millions of rows and columns. Users can quickly access information from these tables using SQL, and the results are displayed in the most popular formats, including tables and related graphs and visualizations.
With the demands of Big-Data and real-time applications and the rising prevalence of unstructured data, No-SQL databases like MongoDB, Cassandra, etc. have gained popularity; however, SQL databases still occupy the top seven positions of the list of the ten most widely used database engines. In order to increase their acceptance in organizations where conventional SQL-based databases are already in use, No-SQL databases have actually positioned themselves as No just SQL to emphasize their support for SQL.
The simplicity of use of SQL is another factor in its appeal. Anyone can quickly learn the syntax because it is so simple to understand. Understanding what the following statements do is very simple.
SQL is a simple language to learn, and hiring managers can use it to quickly and effectively assess applicants’ aptitudes in logic, coding, and data science. Our analysis of 903 data science interview questions revealed that coding is the most common category. Since writing SQL queries was frequently the most important concept tested in the coding segment, it makes up nearly a third of all interview questions.
These top companies ask more SQL-based interview questions than Python or R-based ones. Learning SQL is a good idea because data management skills are becoming more important. So, what should one focus on while honing their SQL skills for positions in data science and related fields?
Real Data Science SQL Interview Questions and Answers # 2 | Data Science Interview Questions
How to Structure SQL Interview Questions
If you’ve ever conducted technical talent interviews, you are aware of the pressure to accurately evaluate candidates’ abilities, experiences, and fit.
The traditional way to begin this process is with a technical interview. But does your strategy enable you to get the solutions you require while also making a strong first impression on potential hires?
To get the inside perspective on running a brilliant SQL-focused technical interview, and evaluating candidates, we had a chat with two experts: Wendy Lu, Growth Analytics Lead at Figma, and Jonathan Geggatt, VP of Engineering at CoderPad (and formerly Head of Data at Airbnb).
Here’s what they told us.
Mine the real world for scenarios that resonate.
How useful is it to ask the SQL interview questions that come up in a simple Google search when candidates have already practiced them?
Because of this, top companies are increasingly moving away from generic questions and giving applicants the chance to try out real-world internal scenarios. “At Airbnb, we provided access to the tools we use and a vetted data set, one in which we were aware of its shortcomings,” It enabled them to concentrate on the shape of the data and formulate solutions to issues that were significant to us, says Geggatt.
Lu agrees that a case-based interview is optimal. I’m not fixated on the toughest questions, but rather the ones that are most pertinent to the day-to-day business issues we’re working on, she says. “More businesses are searching internally for case-based inquiries because they’re useful for comprehensive testing. They can assist candidates in demonstrating their critical thinking, technical proficiency, business savvy, and communication skills. ”.
Yes, it’s obvious, but make sure the skills you’re testing correspond to the candidate’s level of experience. According to Geggatt, there aren’t many conceptually difficult elements in SQL that need testing. He designs interviews to see if a candidate’s claimed experience matches reality and what is required for the position. For instance, an entry-level employee should be able to explain the various join types, whereas a mid-level employee should be able to demonstrate a firm understanding of window functions and aggregations, as well as how they interact and when they would be useful.
He claims that using a dirty dataset for senior level candidates, where a potential employer cannot be certain the data quality is of the highest caliber, is a good way to gauge higher-order skills Watch how well they clean it up, such as by removing duplicates or changing the currency to numbers rather than strings. Data manipulation to increase dataset fidelity is a common real-world scenario.
Offer problems that require conceptualization and application.
Candidates won’t be able to ace a technical interview by studying for it like a test if you’ve game-planned it well. Prioritize candidates’ ability to apply ideas in a thoughtful manner rather than how well they can recite the fundamentals. In a SQL interview, you might ask them to:
Technical interviews are somewhat akin to elementary school; you want applicants to express their ideas, exhibit their work, and raise their hands as necessary throughout the interview. Set that expectation up front, and also make it clear that you anticipate them to look into each issue more thoroughly.
“Technical interviews aren’t always straightforward. Candidates should anticipate that what we’re providing them with has some nuance, says Geggatt. Before responding, they ought to consider what you might be getting at or even what might be missing. ”.
Similar to this, you should check to see if a potential employee is prepared to ask questions if they run into difficulties. It gives you a glimpse into how that person might interact with their team and whether they’ll push forward or cooperate, he says.
The importance of being willing to inquire is stressed by Lu. She observes that some applicants will wait five minutes before asking questions. “That’s a red flag around communication. Sometimes it’s because they don’t want to appear foolish, but there isn’t always a right answer. It does demonstrate how this person might cooperate with others in a group. I want to be aware of the assumptions they’re making so I can challenge them and move the interview along. ”.
Before the tasks – What can you expect in an SQL technical screening?
There are typically two methods for conducting an SQL tech screening.
The easier but less popular approach is to gather a computer, a set of data, and a task. The interviewers are listening and posing questions as you complete the task. As long as you can find the right answer in a timely manner, a little trial-and-error is totally acceptable.
The whiteboard interview is an alternative that is more challenging (and surprisingly much more popular). In this case, you don’t get a computer. You must complete the assignment and draw the code on a whiteboard. This implies that you won’t receive feedback regarding logical or syntax errors in your code (at least not from a computer). Of course, using iterative thinking will still help you complete the tasks. You can solve the various SQL issues one at a time, but you must have great confidence in your SQL abilities.
Additionally, you typically have to complete the tasks immediately. The most you can anticipate is that you might have 3-5 minutes to think.
I know, this sounds stressful. And it is. But don’t worry, there is some good news, as well. Companies will give you relatively easier tasks because they are aware that this type of interview is stressful compared to the challenges you would face in the real world. (See the difficulty level below!).
FAQ
What SQL does CoderPad use?
You can design unique MySQL and PostgreSQL database environments using CoderPad.
How does CoderPad interview work?
Developing an interview pad A pad is a session where the interviewer and the candidate write and run code, either during a live, collaborative interview or a take-home project. CoderPad records everything so that your team can review and share it later. Live interviews are available on all CoderPad plans.
What are good SQL interview questions?
- Q1. What is normalization? What are the different normalizations?
- Q2. What is denormalization?
- Q3. What are the various collation sensitivity types and what is collation?
- Q4. What do you understand about CASE statements?
- Q5. What are some common SQL commands?
How do I prepare for SQL interview?
- Data Definition Language (DDL) keywords.
- Data Manipulation Language (DML) keywords.
- Data Control Language (DCL) keywords.
- Transaction Control Language (TCL) keywords.
- SQL constraints.
- JOINs.
- indexes.
- transactions.
