Top 14 RDBMS Interview Questions (With Example Answers)

By Indeed Editorial Team

Published 11 May 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Preparing for interviews is one of the best ways to maximise your chances of succeeding, allowing you to anticipate questions and prepare responses. If you are planning to interview for database manager or data architect positions, you can expect a few questions on RDBMS (relational database management system) topics. Learning how to answer these questions can help you prepare your responses in advance and feel more confident during the interview. In this article, we describe the differences between RDBMS and DMBS, explore some of the most typical RDBMS interview questions and look at example answers.

Related: What Is The Difference Between DBMS & RDBMS? (With Examples)

Commonly asked RDBMS interview questions

Here is a list of 14 common RDBMS interview questions, along with example answers that you can use to craft your own responses:

1. Can you name the three primary features of an RDBMS and explain what each represents?

Technical questions such as these enable interviewers to examine the extent of your knowledge of RDBMS. It is best to answer the question clearly and directly, explaining the features at length to show that you understand how they differ from each other.

Example answer: 'The three primary features of an RDBMS are attributes, names and tuples. Firstly, attributes are the columns in relations. Names are the specific names for the relations in the database, and tuples are the rows in each relation.'

2. Can you name the four kinds of keys in an RDBMS?

It is typical for employers to ask about keys because they are essential components of RDBMSs. If you cannot remember all of them, try to name at least some and describe their functions. Naming some of the keys can show that you possess relevant knowledge.

Example answer: ‘The four kinds of keys are primary, foreign, super and candidate keys.'

3. Can you describe an index and name the different types?

This question frequently arises as recruiters want to know how well you understand this important aspect of RDBMSs. It is crucial to recall the names of the indexes if you cannot remember their functions. Overall, there are three indexes to consider.

Example answer: ‘Professionals use indexes when they want to tune the performance of a table and retrieve records more quickly. These methods come in three types: clustered, non-clustered and unique.'

4. What is a buffer manager and what are their primary responsibilities?

A buffer manager is not a job title but a software module that completes tasks relating to an RDBMS. You can differentiate yourself from other candidates by expressing your knowledge of this component. A buffer manager helps improve the efficiency of databases.

Example answer: ‘A buffer manager works by collecting data from storage disks. Then, the software sorts the data and places some in the memory cache. It does this to improve processing speeds.'

5. What is a subsystem and can you describe a few of the RDBMS subsystems?

Subsystems are an important technical topic to revise before your interview. Subsystems serve as the basis for an RDBMS. While recruiters probably do not expect you to name all of them because there are so many subsystems, naming a few can help you show them that you are familiar with the topic.

Example answer: ‘Various subsystems exist in an RDBMS. The term refers to smaller systems within a larger system that serves various functions. Certain subsystems tackle language processing and transaction control, while others control storage and memory management.'

Related: What Is DBMS? (Types, Benefits And RDBMS Vs DBMS)

6. What is normalisation? Explain the different types of normalisation.

You can expect to receive a question such as this, as it tests your knowledge of improving databases. Attempt to define the term clearly before explaining the different types of normalisation. While recruiters usually do not expect you to name all the types, it is essential to know at least three or four to demonstrate your understanding.

Example answer: ‘The process of normalisation removes redundancy and improves consistency when organising data. There are several types of normalisation, including 1NF, 2NF, 3NF, 4NF, 5NF and BCNF.'

7. Listing as many as you can, what are Codd's 12 rules for relational databases?

It is important for you to revise Codd's 12 rules for relational databases. Recruiters ask this advanced question to examine your knowledge. Knowing about all 12 rules can help you impress the interviewer. Try to recall at least five or six to prove that you understand the concepts.

Example answer: ‘I know that rule zero focuses on qualifying databases, rule one is about information and rule two is the guaranteed access rule. I believe rule number three refers to the systematic treatment of null values and rule four refers to active online catalogues. Also, if I remember correctly, the fifth rule concerns the complete data sublanguage rule and number six is the view updating rule.'

Related: Important DBMS Interview Questions And Answers To Ace Your Meeting

8. What does RDBMS stand for and what are its capabilities?

This is a basic question that recruiters can ask to ensure you have a fundamental knowledge of RDBMS. It is important for you to answer this question without hesitating. Answer directly by naming each letter of the acronym and what it stands for.

Example answer: ‘The acronym RDBMS means relational database management system. This is a more comprehensive version of the standard database management system. It builds on the efficiency of data access and storage of the earlier version.'

9. From your own knowledge, tell me why an RDBMS is a viable option to traditional file-based systems.

You can potentially rely on your own experience to answer this question. If not, try highlighting a few aspects of an RDBMS and explaining why it is much more effective than a traditional file-based system. You can answer this question effectively by naming two or more reasons.

Example answer: ‘From my knowledge, an RDBMS is more viable because traditional file-based systems lack indexing capabilities. Using them requires scanning the entire page, which can be time-consuming and tedious.'

10. What are the various languages that you can find within an RDBMS?

You can mention several languages to answer this question, as there are many computer languages within RDBMSs. The recruiter typically does not expect you to name all of them, so it is best to focus on the ones you know the most. Ideally, attempt to name at least three languages.

Example answer: ‘I'm most familiar with the data definition, data manipulation, transaction control and data control languages.'

11. What does the acronym ACID represent, and what are the different ACID properties?

Describe each letter in the acronym in one brief sentence to answer this question. If you cannot recall what each letter means, saying what each represents is adequate. If you have more time, you can go into further detail about each letter to highlight your knowledge.

Example answer: 'ACID stands for atomicity, consistency, isolation and duration. Atomicity means performing all data changes successfully or not at all. Consistency means keeping data consistent before and after transactions. Isolation means that while the transaction is in operation, no other process can change the data. Durability refers to the persisting changes that the transaction makes.'

12. What is data warehousing, and why is it important for an RDBMS?

This is a practical question to test your common knowledge. Give a brief definition of data warehousing and, if possible, explain why it is significant to an RDBMS. Try to be concise with your response.

Example answer: ‘Data warehousing is collecting, manipulating, extracting, changing and uploading data from various sources into one singular database. It is important because it serves as a central location for all the data in an RDBMS.'

Related: Relational Database Management Systems: MSSQL Vs MySQL

13. What are TRUNCATE and DELETE? What are their primary differences?

Commands are an important aspect of the job, so your recruiter is likely to question you on your knowledge of these two commands. Be sure to distinguish between the two in terms of their unique functions. A direct explanation of each term is enough to answer the question.

Example answer: ‘The TRUNCATE command is necessary for removing complete data from within the table of a database. Comparatively, the DELETE command is for deleting entire rows from a table.'

14. What are the different levels of data abstraction?

There are three distinct levels of data abstraction for you to consider. You can answer this common knowledge question with a brief definition of each level. Make sure that your explanations are notably different from one another to show your expertise and confidence in answering the question.

Example answer: ‘There are three levels of data abstraction, including physical, logical and view. The physical level describes how to store data and it is the lowest level. Logical data abstraction is the middle level and describes the type of data that is in the database.'

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