Simple SQL questions for recent graduates explained in plain language
If you are a recent graduate looking to start a career in technology, SQL is one of the most common topics in interviews. Whether you are aiming for a data analyst position or a job in software development, knowing the fundamentals of SQL gives you a clear advantage.
What is SQL and what is it used for
SQL stands for Structured Query Language and is used to work with data within a database. With SQL you can insert records, search for specific information, update data, or delete entries. It is fast, reliable, and most companies use it to manage information.
WHERE vs HAVING
WHERE is used to filter rows before any grouping. HAVING is applied after grouping data with GROUP BY. For example, to find departments with more than 5 employees, you would use GROUP BY department and HAVING COUNT employee > 5.
Primary key
A primary key is a field or combination of fields that makes each row in a table unique. It serves to identify records without ambiguity and usually has a constraint that does not accept null values.
Types of JOIN
INNER JOIN shows only the rows that match in both tables.
LEFT JOIN shows all rows from the left table and the matches from the right.
RIGHT JOIN shows all rows from the right table and the matches from the left.
FULL OUTER JOIN shows all rows from both tables, combining matches when they exist.
DELETE vs TRUNCATE vs DROP
DELETE removes selected rows and can use WHERE. TRUNCATE removes all rows quickly and usually resets counters, but does not allow WHERE. DROP removes the entire table including its structure.
Foreign key, normalization, and subqueries
A foreign key connects two tables, allowing references between records to be maintained. Normalization organizes data to reduce duplication and improve integrity. Subqueries are queries within other queries and are used for more complex operations or filtering dependent on intermediate results.
Tips for preparing for interviews
Practice 30 to 45 minutes daily by writing and testing queries on free online tools. Solve real exercises such as listing employees who joined in the last 3 months. Conduct mock interviews with friends and take beginner courses in your language. Also learn business intelligence concepts and tools like Power BI to complement your profile.
How Q2BSTUDIO can help you
At Q2BSTUDIO, we are a custom software and application development company specialized in modern solutions. We offer custom software, custom applications, artificial intelligence services, and AI agent development for businesses, as well as cybersecurity to protect your systems. We work with aws and azure cloud services and offer business intelligence services integrating Power BI so that your data adds value. We also develop AI solutions for businesses that automate processes and improve decisions.
If you are looking for practical training or real projects to improve your resume, at Q2BSTUDIO we design custom challenges that combine SQL, business intelligence services, cloud pipelines, and artificial intelligence models ready for production.
Final reflection
Do not be intimidated by long definitions or advanced syntax. Start with the basic questions, understand the logic behind each query, and practice daily. With consistency, you will confidently answer most SQL questions in an interview and also stand out by offering knowledge of custom software, custom applications, artificial intelligence, AI agents, cybersecurity, aws and azure cloud services, business intelligence services, and Power BI.
