DBMS is a database management software that provides an interface to perform various operations like creating new databases, adding data, updating data, deleting data, retrieving data, etc. DBMS also provides protection and security to the database. It reduces data inconsistency and redundancy to make data more reliable.
DBMS is one of the most important topics for college placements as well as gate exam. In this article we go through the top 10 DBMS interview questions. These questions were asked in most of the DBMS interviews.
Top 10 DBMS interview questions:
1. What is DBMS?
Answer: DBMS stands for Database management System. DBMS is a software which is used to manage databases. It is used to insert, delete, update and retrieve data from the database by running some queries. It acts as an interface between the user and the database. Examples: MySQL, Oracle, SQL server, PostgreSQL and Microsoft Access.
2. What are the advantages of DBMS?
Answer: Some advantages of DBMS are:
Improved data sharing and integrity: Multiple users can simultaneously access the same data at any point of time.
- Reducing data inconsistency: Data inconsistency occurs when different versions of the same data occur in the database. DBMS helps to design the databases properly to reduce the data inconsistency.
- Reducing data redundancy: DBMS designs databases in such a way that duplicate data can’t be inserted in the database.
- Simple: DBMS gives a simple and logical view of the data. The operations like insertion, deletion and updation are easy to implement with the help of DBMS.
- Data abstraction: Developers use complex algorithms to increase the efficiency of the database. DBMS hides these complex algorithms and provides an abstract view of the database to the user.
- Increase end – user productivity: DBMS provides tools to convert the data into useful information, which helps the users to make quick and correct decisions.
- Increase security: DBMS provides tools like authentication and encryption to make data more reliable and secure.
3. What is a Database?
Answer: A database is an organized and systematic collection of data, which is stored electronically on a computer. The database helps in managing large amounts of data efficiently. A software called DBMS can be used to extract data from the database by running some queries. A database consists of sets of tables or objects which contain records and fields. A row in the database represents a single entry and columns define the attributes which define a particular aspect or property of the table.
4. What is normalization?
Answer: Normalization is the process of reorganizing data to remove data redundancy and eliminate insertion, updation and deletion anomalies. Normalization ensures data is stored logically in the database. This is one of the most important DBMS interview questions. The normal forms in SQL are:
- 1NF (First Normal Form)
- 2NF (Second Normal Form)
- 3NF (Third Normal Form)
- BCNF (Boyce-Codd Normal Form)
- 4NF (Fourth Normal Form)
- 5NF (Fifth Normal Form)
- 6NF (Sixth Normal Form)
5. What do mean by durability in DBMS?
Answer: Durability ensures that once a has been completed and committed into the database, it should be stored in a non-volatile memory and even a system crash cannot affet that data anymore. Once the DBMS informs the user that a transaction has completed successfully, its effect should persist even if the system crashes before all its changes are reflected on disk. This property is called durability.
6. What is data warehousing?
Answer: Data warehousing is the process of collecting relevant data from various sources to provide business insights which help the business analyst to make correct and reliable decisions. It is the process of storing large amounts of data electronically which is designed for query and analysis instead of transaction processing. It converts data into information needed for business growth.
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7. What is data modeling?
Answer: Data modeling is the process of cleaning and organizing data into a visual or graphical representation to get useful insights and map out the connections and relationships needed at the database level. Benefits of data modeling:
Data modeling improves data quality and makes databases less prone to errors and poor design.
Data modeling creates a visual flow of data and how you plan to organize it. This helps employees understand what’s happening with data and how they fit into the data management puzzle.
Data modeling improves data-related communication across departments in an organization.
Data modeling creates database design which can bring forth better applications and data-based business insights down the line.
8. What are different types of data models available?
- Conceptual Data Model: The model is used to define the relationship rules. This model defines what the system will contain. This model is typically created by Business stakeholders and Data Architects. The purpose is to organize, scope and define business concepts and rules.
- Logical Data Model: This model expands on the conceptual model but considers more relational factors. This model defines how the system should be implemented regardless of the DBMS. This model is typically created by Data Architects and Business Analysts. The purpose is to develop a technical map of rules and data structures.
- Physical Data Model: This model is the final step before creation of the database. This Data Model defines how the system will be implemented using a specific DBMS system. This model is typically created by Database administrators and developers.
9. What is RDBMS?
Answer: RDBMS stands for Relational Database management System. RDBMS is a software which is used to manage databases. It is used to insert, delete, update and retrieve data from the database by running some queries. It acts as an interface between the user and the database. It is a more advanced version of DBMS. RDBMS stores data in tabular format whereas, DBMS stores data in file format. RDBMS supports distributed databases and can handle large amounts of data.
10. What is the difference between the primary key and foreign key?
Primary key: Primary key is used to uniquely identify the entries in the table. It can access a particular record in the table. Primary keys are always unique, there can’t be duplicate primary keys.
Foreign key: Foreign is the key in a database which is connected to the primary key in the original table. In a simple language, a foreign key refers to the primary key in another table.
Also you can prefer this DBMS Interview Questions article for better understanding, go and check it out!
We tried to discuss DBMS Interview Questions in this article. We hope this article gives you a better understanding of the type of DBMS questions you will face in the Interviews. Prepbytes also provides a good collection of Foundation Courses that can help you enhance your coding skills. Want to make sure you ace the interview in one go? Join our Placement Program that will help you get prepared and land your dream job at MNCs. Mentors of Prepbytes are highly experienced and can provide you with basic, in-depth subject knowledge for better understanding.