RDBMS Interview Questions

Are you looking for a job in the RDBMS space? If yes, then you are absolutely right on the track as we are about to dive deep into the nitty-gritty of the Relational Database Management System. These fundamentals will help you in passing your next interview and evaluate your current skills level too. In this blog, we have covered maximum questions related to RDBMS that you may encounter during an interview. So, let us practice them in advance and increase your chances of getting hired by top companies worldwide.

RDBMS Interview Question and Answer

Q1). Give a quick idea of the term RDBMS?

It helps in storing or managing data across multiple tables. The best part is that you can define relationships among different data entries using tables. Relationships are generally expressed through values, not pointers.

Q2). How will you define a relational database model?

It defines the relationship among different databases and how are they connected. When multiple databases are connected, it creates flexibility and can be used within a software app as needed.

Q3). Tell me about RDBMS components?         

Each relation in an RDBMS is given a “Name” that will be unique among others. There are rows and columns in each relation columns represent attributes and rows as Tuples.

Q4). Give a quick idea of the term Normalization.

It is a data organization process where data is organized in such a way that it can minimize the redundancy. It divides the database into multiple tables and defines logical relationships among them.

Q5). Name different Normalization types that can be used with RDBMS?

Each has its objectives and purpose. So, you must understand them one by one before implementing with the database.

Q6). Have you ever used a Stored procedure (SP) in RDBMS?

Yes, I know about the SPs and worked on the same during my training work. A SP is a group of SQL statements that can be used together to act. It accepts input parameters to be used with different scenarios. To ensure the integrity of a database, SPs are considered an added advantage.

Q7). Give me a quick idea of the E-R Model.

It is consisting of entities and relational objects. Entities can be understood by the collection of attributes in the database.

Q8). Tell me something about various data abstraction levels?

In RDBMS, data can be abstracted at three different levels. They are given below in the diagram.

The physical level is available at the bottom, giving you a detailed idea of the data storage. The Logical level at the next stage finds the logic among data tables and how to group similar data for easy access. At the top, there is a view level that gives information about the complete database and various views of a database.

Q9). Define the term trigger about the RDBMS.

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It is a stored procedure that acts as soon as some event occurs. Events are not called by the programmers but invoked automatically as soon as edits are made systematically.

Q10). What is a VIEW, and how will you define it?

A “view” is a subset of a database used to retrieve, delete, or combine the data. As soon as you edit a view, original data also changes in the table.

Q11). Do you have any idea of INDEX storage in RDBMS?

For creating pointers to the data, indexed are used. They help in finding rows in a table quickly. Indexes can be defined for multiple columns together with a different name. They cannot be seen or accessed by users but helps in improving the database performance. For small tables, impacts can be negligible. In the case of complex data tables, the impact of indices is clearly visible.

Q12). There are two types of indexes in RDBMS. Can you tell me their names and the significance?

Yes, there are two methods for index storage in RDBMS. These are given below.

Clustered indexes can give information about the physical storage of the data and non-clustered indexes will give you an idea of logical ordering.

Q13). How are RDBMS preferable option over the DBMS?

It minimizes the redundancy and integrity can be maintained. It maintains data consistency and allows data sharing to other databases. It follows a set of rules to satisfy storage standards and maintains security.

Q14). Tell me about buffer manager?

A buffer manager transfers the data from third-party storage devices to the memory and puts some data into the cache for easy access.

Q16). Tell me about Keys and how are they valuable?

A key is a constraint added to a database for restricting the data access requirements. These are important for any database to maintain maximum data integrity.

Q17). How many keys can be applied to a database?

There are different types of keys that can be applied to databases as needed. Here we have listed the names of popular ones that are used frequently.

Q18). What is the most common key that can be applied to almost all database

It is the Primary Key. There is only one Primary key in one table.

Q19). If multiple columns have to be used as a Primary key, then what it is called?

It is a Candidate Key.

Read: All About SQL Joins and Subqueries

Q20). If we are using the Primary key from any other table, then what it is called?

It is a Foreign key that is used to maintain referential Integrity.

RDBMS Interview Questions for Experienced

Q21). Explain about Codd’s 12 rules for an RDBMS?

Codd 12 is a list of 13 rules starting from 0 to 12 that should be satisfied by each relational database model:

• Each database should define one relation.
• Information should be given uniquely in terms of rows or columns.
• Each scalar value within a database is defined logically.
• Null values should be addressed wisely for each tuple.
• Database structure needs to explain well for each table.
• The system should satisfy one relational language.
• The database should be divided into various Views carefully.
• The system should satisfy various events.
• For each application, integrity constraints should be defined in advance.
• Focus on the physical data storage and various data structures.
• Distribution of a database to multiple locations should not be visible.
• Check the system for the low-level interface. In this case, it cannot be divided.

Q22). What are the two specific rules that you should follow for each RDBMS to maintain the data integrity?

These are divided into two categories that are necessary to learn by every RDBMS expert. 

To maintain the integrity of an Entity, the Primary key should never contain the NULL values. To maintain referential integrity, the foreign key should be used that is defined as the Primary key for another table.

Q23). RDBMS follows an object-oriented approach or not?

Well, I think RDBMS follows the object-oriented approach. Object-oriented model is defined based on the collection of objects. An object instantiates the value stored in instance variables. If objects are sharing the same properties or methods, then they can be grouped to form a class. The same process is followed in RDBMS as well.

Q24). How memory storage can be optimized in RDBMS?

You should use a buffer manager for memory optimization in RDBMS. A buffer manager puts the data from third-party storage devices to the main memory. The frequently accessed data is stored in the cache for quick access.

Q25). How will you compare Intension and Extension terms for a database?

The Extension defines the total number of tuples available within a table at an instance. They are dependent on time. Intension may be a constant value that gives a sound idea of constraints, name, and the structure of a table.

Q26). How to check the feasibility of RDBMS?

To check either it is possible building a relational model or not, you should use System R in that case. It will check the compatibility of the relational model with the real-life environments and performs the performance study too.

Q27). Name two major subsystems of System R.

   

Q28). How to define “Data Independence” standards in a database?

Data independence means making an application independent of the storage structure and the strict data access strategy. The data modification made at one level should not impact the other. For example, if changes are made to the physical level of data abstraction, then it should not impact the logical data abstraction layer. When this independence is established for a database, it becomes more reliable, robust, and secure.

Q29). How can views be named as Data independence standards?

A “view” is defined as a subset of a database or tables stored in it. It can be used to retrieve, delete, or combine the data. Each View can be taken as a separate table and accessed for the application. When changes are made to a specific VIEW, it will not impact others. This is the reason why VIEWS should be learned first to understand the concept of Data Independence in detail.

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Q30). What is a Weak and Strong Entity Set according to your past experiences?

An entity can be taken as an object or thing with independent existence. An entity set is a collection of all entities within a database. Sometimes, an entity set does not have all the necessary attributes to define key constraints and other logical relationship then it is termed as the weak entity set. If an entity set has all necessary attributes to define the primary key and other constraints, it is termed as a strong entity set in that case.

Q31). What do you understand by terms DDL, VDL, SDL, and DSDL in RDMS? 

• DDL can be defined as the database schema that specifies a set of definitions through a special language called DDL.
• VDL that gives information about views and their mapping with the conceptual schema.
• SDL that gives information about the internal schema and defines the relationship among two storage schemas.
• DSDL defines the storage structures or access methods utilized by databases.

Q32). What are the different relational operators that can be applied to a database?

A wider range of relational operators that can be applied to a database can be given as:

• A Union operator is used to combine multiple rows to avoid duplicate content.
• An intersect operator is used for finding common elements within a row.
• A Cartesian operator is used as a cross-join operator to apply on two relations.
• A difference operator is used to identify the different values in multiple rows.

Q33). What is the significance of ACID properties for a database?

These four properties are considered highly important for any database. These properties make a database easy to access and use. It is possible to share data among tables conveniently. Also, it focuses on data accuracy and avoids redundancy.

Q34). How are DBMS and RDBMS different from each other? Give some meaningful differences.

DBMS tells about the data storage and data creation. RDBMS explains about relations among tables and data values. DBMS operations can be used for a specific database, but RDBMS can work on multiple databases together.

Q35). When designing a database, how many relationships you can define?

When designing a database, three types of relationships can be defined. These are: 

Q36). As we know, there are various normalization forms. So, can you explain the difference between 4NF and 5NF?

In the 4NF, it should satisfy the 3NF, and it should not contain two or more views about an entity. In the 5NF, we can reconstruct the information from small pieces of content so that they can be maintained with maximum consistency.

Q36). One of the biggest challenges faced by system architects is delivering maximum throughputs so that millions of transactions can be exceeded per second. So, how will you handle this challenge with care? Justify your answer based on your previous work experience.

Whenever you are working on the big data problems, it should be handled with care. Let us understand the concept with three technical terms Data Ingestion, Transformations, Storage & Analytics.

Data Ingestion uses technologies like Apache Kafka and streamlines the data across different targets gracefully. The second term is transformation, where data is reconstructed and transformed into a meaningful real-time solution.

The last term is Storage & analytics, where No SQL database can be utilized to manage all data issues and works on consistency problems eventually. Once you are done with it, these three features can give you more flexibility, high throughput, and low-latency benefits. In brief, we should replace the traditional batch-oriented approach with modern streaming solutions.

Final Words:

The blog gives you a sound idea of RDBMS interview questions that you may encounter in your next interview. The discussion always starts with basics like RDBMS, Normalization, Triggers, Views, etc. After this, the interviewer will check your practical knowledge through different example. So, the blog is enough to practice theoretical RDBMS concepts. To learn the practical aspects of RDBMS and how it is used by Companies, join the RDBMS certification course at JanBask Training, start exploring the world-class RDBMS systems now.

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