Do you think your basic SQL knowledge is enough to clear that first tech interview? 

Think again. 

Many freshers walk into their SQL interviews confidently thinking they will be able to work through the basics like SELECT, JOIN, WHERE, and so on. But throw in a real-world query or logic-based scenario from the interviewers, and it all falls apart.  

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Knowing SQL syntax is not enough. What separates the candidates who got offers from those who missed it is often a thorough understanding of how a query works internally, data retrieval optimization, and the usage of SQL in actual business applications.  Most of the time, freshers miss out on their offer because they have prepared the wrong way, rather than not studying enough. Be it due to the misuse of JOINs, confusion about GROUP BY, or difficulty working with subqueries, the patterns repeat themselves.  

Why SQL Is a Must for Freshers in Tech  

Whether you want to be a Data Analyst, a Software Developer, a Business Analyst, or a QA Tester -- you will need SQL. Here are some reasons why every fresher should have it on their skills list:   

• SQL is the data language. Almost every organization needs its data stored in a relational state and SQL helps with all of it.  

• It is included with ensuring you have a technical interview. SQL questions are a consistent part of an entry-level role in virtually all of the IT space.   

• Back-end systems use SQL. Whatever the application may be, an e-commerce site, a fintech web app, or even a game, logic is powered by data queries.   

• It helps with data analysis. Running SQL code allows you to extract immediate insights from large datasets.   

• It is used by positions other than IT. Marketing Analysts and Product Managers need insights from data-driven user behaviour and often use SQL.   

• SQL demonstrates that you can demonstrate planned or structured thinking. It is a large part of logical reasoning, recognizing patterns in thinking, and understanding relationships in data.   

• It is your key to learning. Demonstrating an understanding of SQL, makes moving to advanced learning Data Science, Business Intelligence or Big Data tooling easier.   

To summarize, SQL is more than just another language, is a technology schema. The sooner you learn it, the sooner you will move forward and on in your career. 

7 SQL Interview Questions Most Freshers Get Wrong  

You’ve memorized the SQL commands. You've run a couple of queries for practice. Then that ill-fated moment comes when the interviewer asks a slightly different one, and you freeze out.   

You're not alone. A lot of freshers stumble upon questions that assess logic rather than rote syntax.    

Let's jump right into the frequently asked SQL interview questions puzzling the not-so-advanced, what makes them tricky, what answers freshers usually give, and what the interviewer is looking for.  

1. What is the Difference between WHERE and HAVING?  

Some of the new candidates say, "Both are used to filter data," and that is the end of the matter for them. Some are even mistaken enough to say HAVING is merely a snazzier term for WHERE.   

The real nitty-gritty is that WHERE and HAVING work at completely different stages in a SQL query. So, WHERE filters rows before grouping takes place or before aggregation happens? HAVING, instead, happens after the grouping, and it's present to filter the results of aggregate functions such as COUNT, AVG, or SUM.   

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 Say, for example, you're trying to find departments with more than 10 active employees. Then, first, you filter active employees using WHERE, and with groups whose counts are above 10, HAVING comes into play. An interchange of the two might result in wrong output or even worse, syntactical errors.  

2. How Does GROUP BY Work Internally?  

Freshers often say, "It just groups rows with similar values." While it's not necessarily incorrect, it is a bit of an oversimplification.  GROUP BY does not collect just any similar row; it restructures the dataset based on the column(s) you choose to group by. Once the grouping is done, SQL applies aggregate functions to each group.  

At this point, it limts what you can specify in your SELECT clause. You cannot simply list non-aggregated columns unless they are in the GROUP BY. I would say that most candidates get this wrong while writing queries.  

This understanding would help you write better reports, summaries, and dashboards—something very much appreciated by employers.   

3. Write a Query to Fetch the 2nd Highest Salary from a Table 

This is a classic. Most freshers will often quickly jump to use ORDER BY with LIMIT or TOP clauses i.e. "Just give me the salaries in descending order and choose the second." 

This works sometimes and could differ across SQL platforms. Not every database supports LIMIT or OFFSET syntax. Moreover, if there are ties for top salary, this logic fails. What interviewers are looking for is your ability to develop a problem logically without looking for a quicker way. One of the common methods is to fetch the maximum salary that is less than the highest salary, via nested queries. Even better? They simply love it when you then explain why this method is better, more portable, and more accurate.  

4. What’s the Output of this JOIN query?  

Here, you have two tables - let's say students and courses. Some students belong to multiple courses and others don't belong to any course at all. Then you're asked what the result of an INNER JOIN of the two tables will be.   

The most common incorrect answer will be "It will show all the students and their courses."   

That's wrong because INNER JOIN only returns rows where there are matches in both tables. For example, for the students who have not enrolled in any courses, those rows are omitted. Similarly, any course row that doesn't have a corresponding student ID is dropped as well.   

The interviewer is using this to see how well you understand what a data relationship is and how JOINs work. This isn't just a definition.  

5. What’s the Difference between INNER JOIN, LEFT JOIN, and FULL OUTER JOIN?  

Most freshers will just say a line like this: 'INNER JOIN will get me common data, LEFT JOIN will get me data from the left, FULL JOIN will get me everything.'  The interviewer is probably looking for a little more detail.  

 What you explain:   

• INNER JOIN only returns matched records from both tables.   

• LEFT JOIN contains all records from the left table and matched records where they existed on the right. The unmatched rows from the right-side table appear as NULL.  

• FULL OUTER JOIN retrieves every record from both tables, filling in NULLs wherever a matched record is missing on either side.   

What impresses interviewers more than anything is when you add a real-world example - if I wanted to get a list of all customers, I would use a LEFT JOIN because I still want to know who has not placed an order.  

6. Why is SELECT * Discouraged in Real-World Queries?  

Most beginners say, "It's easier to use," or "It will grab everything all at once."   

What they fail to recognize is that the real-world databases they will be dealing with are huge. Selecting all (*) will select every column, regardless of whether it is needed or not. This may result in slower queries, heavier load on the network, larger applications, and so on. Additionally, it is dangerous. If someone adds a column to the table tomorrow, that column will populate your code, and your application can break or return unexpected results.  

Interviewers want to see you understand the fundamentals of selecting only what you need from a performance and clarity perspective. This indicates to them that you write SQL that is maintainable and scalable, not only SQL that is functional.  

7. What’s the Difference between DELETE, TRUNCATE, and DROP?  

Newcomers to the world of SQL usually group them together with that umbrella term: “They all delete data.” Technically, that's true, but it is also a significant understatement. DELETE removes rows, but at the row level, you could roll back the command if you used a transaction. It is the most targeted, but the slowest (especially with very large datasets).   

TRUNCATE removes all the rows from a table, instantly, and in many database implementations, you cannot roll back the command. It is faster because it doesn't log the removal of the individual rows. DROP goes a step beyond—this command deletes the table structure, so the table and its data are gone.    

The importance of knowing these differences is not only for academic purposes. In production, using the wrong command can result in significant data loss, and employers want people to understand the implications of each command.  

How Fusion Software Institute Helps You Prepare for SQL Interviews  

At Fusion Software Institute, we don't just teach you SQL and that's it. Instead, we teach you how to think like an interviewer and solve like an expert. Our training on SQL doesn't just teach you how to talk about building SQL queries—I will be helping you build a meta-skill in query solving and understanding how databases work in a corporate environment.  

As you can experience throughout your time with us, your training will use hands-on extra practice sessions, mock interviews, and every student's unique mentoring style. Throughout your training you will be learning about how to implement logic-based SQL and how to understand yourself in using it, fixing slow queries and, more seriously, teaching you to avoid mistakes new freshers make.  

The training you will receive is governed and written up with a base by SMEs, asking queries of Industry and Training Mentors. Therefore, you will be 'interviewer prepared' from day one; alongside understanding live projects, and thinking about and responding to a case, you're not just coding, you're solving real business problems, In the form of learning.   

Whether the first job you are going to work on or if you're switching roles, Fusion creates a knowledge palate that in all seriousness will give you the clarity to hack any SQL interview you might have.  

Ready to Beat the Odds in Your SQL Interview?  

Cracking an SQL interview isn’t about knowing every command, but about knowing how and when to use the commands… The questions we asked today may seem humdrum but reveal more extensive gaps in logic and application-focused knowledge, the knowledge that lots of freshers drag into interviews unknowingly.   

But here's the good news: you don’t have to figure it all out alone.   

We can hel you prepare smarter at Fusion Software Institute, with practical experience, constructive feedback, and expert-led peer advisory boards designed to help you get hired faster than the average bear.   

Want to stop guessing and start preparing the right way?  Join our SQL training program today and turn your interviews into offers.  📞 Call 9503397273 or 7498992609