top 50 dbms interview questions and answers

Top 50 DBMS Interview Questions and Answers 2022

Blog | Board Infinity
Blog | Board Infinity

In every place where a computer is being used, the need for a Database Management System (DBMS) for storing and managing data is inevitable. So, there are hundreds of companies that are looking for employees having expertise, like Oracle, Microsoft SQL Server, MySQL, Hive, etc.

DBMS Interview Questions and Answers will help the candidate to get an idea about the nature of questions that are generally asked during the interview. Let's see the list of the top 50 Database Management System (DBMS) interview questions and answers, for freshers.

1. What is Database?

A database is typically a collection of related data that is electronically stored in a computer system in an orderly and structured fashion. The database management system (DBMS) is the software that interacts with end-users, applications, and other databases.

2. What are Disciplines?

Disciplines are the specific business functions within the data center, such as banking, marketing, manufacturing, customer service, etc.

3. What are the benefits of Data Warehousing?

Data warehousing is defined as an organized collection of data from one or more sources that describe specific characteristics of identifiable entities and is used for reporting or decision-making. It allows an organization to efficiently use time. It also improves the quality of the data as well as secures data at the same time. Effectively being able to combine and assimilate data also helps in improving business intelligence.

4. What is Data Lake?

Data Lake consists of the aggregation of data that has been structured, unstructured, or semi-structured in nature into a centralized repository that can be queried using the standard SQL language against analytic systems (OLAP databases).

5. What is a Data Vault?

Data Vault (DV) is a metadata-driven logical data model. This means that all the metadata about the structure and relationship of the model resides with the DV and not in a separate dictionary, as with more traditional modeling techniques.

6. What is Data Mart?

A data mart is a collection of dimensional data, derived from one or more operational source systems. One can use a data mart to support a business function or an entire organization, such as finance, sales, or marketing. They help in speeding up the business processes by allowing access to information that is relevant quickly, rather than keep the enquirer waiting for a long time.

7. What are the uses of Data Warehousing?

They are used for decision support, performance management, reporting, and analytics. It is used for storing data that is used for one or more than one purposes. It is used for analyzing the data instead of being used for processes involving transactions.

8. What is Enterprise Warehouse?

An enterprise warehouse is designed to provide all organizational information about a business in an electronic format. It keeps and provides information regarding the enterprise’s various consumers, its business data, etc.

9. What is the benefit of Enterprise Warehouse?

It provides a single version of the truth and allows easy access to data that can be used for informed decision-making. It also increases the speed and accuracy of analyzing the data by giving access to all of it under one roof. Giving a boost to efficiency while maintaining the security of data is also an important benefit of an enterprise warehouse.

10. What is Data Integration (DI)?

Data integration involves combining data from distributed heterogeneous sources into consolidated data marts or warehouses to maintain a single version of the truth.

11. What is Data Quality (DQ)?

Data quality is defined as "fitness for use". The data in a system must be accurate, timely, complete, and relevant.

12. What are the three main steps in Data Quality?

They are identification, prioritization, and correction. These steps are generally handled by a formal project known as the DQ Project. To correctly store and analyze data, accurate identification of data is necessary while making sure the most important data is given priority and corrections are made as and when required.

13. What is Data Cleansing?

The process of detecting and correcting or removing corrupt or dirty data from a data warehouse is known as data cleansing.

14. What are some common Data Integration Strategies?

They are ETL, ELT, EII, OLAP cube, data federation, etc. These strategies are used to extract, transform and load (ETL), extract, load, and transform (ELT) data, or analyze data and search for insights using Online Analytical Processing, etc.

15. What is the Common Data Integration Technologies?

Data integration can be achieved through different technologies, such as Extract Transform Load (ETL), Enterprise Information Integration (EII), and Open Database Connectivity (ODBC).

16. What is Data Replication?

The process of copying data from one system to another is known as data replication. The destination system is also known as the data warehouse.

17. What are the requirements of Replication?

The requirements for replication include security, performance, reporting, and online analytical processing (OLAP) capabilities. These requirements help in the decision of whether to use a data warehouse or a data mart.

18. What is ETL?

ETL is a process that extracts raw data from heterogeneous sources like flat files, emails, or websites and loads it into a data warehouse or an enterprise data mart after transforming the data into a dependable and useful resource.

19. What is DQ and how does it relate to ETL?

Data quality and ETL go hand-in-hand because the ETL process must ensure that the cleanest possible data is loaded into the warehouse infrastructure in order to maintain a high level of data quality.

20. What is ELT?

ELT stands for Extract Load Transform and is an alternative to ETL. The difference between the two techniques is that ETL loads data into a data warehouse, whereas ELT loads it into a staging area which can then be transformed before being loaded into the final destination.

21. What are the advantages of DBMS?

DBMS provides speed, reliability, security, and the ability to handle large databases. It helps in the fast retrieval of data and is highly secure. It also allows access to better comprehensive data which is highly consistent. DBMS aids in making better decisions as well as increases the productivity of the end-user.

22. What is Memory Optimization in DBMS?

Each instance of a database has its own memory manager that manages how memory is used for storing indexes, tables, views, etc. Memory optimization is basically the aforementioned functions stored in a manner that is optimal and increases efficiency.

23. What are Transactions in DBMS?

A transaction defines the smallest amount of work that can be committed to or rolled back by the database. Read and write operations are used to access the transactions in the data.

24. What are ACID Properties in DBMS?

The ACID properties are Atomicity, Consistency, Isolation, and Durability. These properties define four key characteristics that a database must possess to be called ACID compliant. Atomicity refers to the full completion of a transaction or non occurrence of one. There exists no mid-way transaction. Consistency refers to the maintenance of the integrity of data in a manner that keeps the data consistent, both before and after the transaction. The isolation property makes sure that simultaneous transactions don’t lead to inconsistency in the data. Durability property in DBMS ensures that the changes and updates made to the data as a result of a transaction stay securely in the database.

25. Who is the Developer for Oracle?

Oracle Corporation was founded by Larry Ellison, Robert Miner, and Ed Oates in 1977.

26. Who is the Developer for MySQL?

MySQL was developed by Widenius and colleagues from 1994 to 1995 and first released in 1996.

27. What are the utilities of DBMS?

DBMS is used to add indexes, analyze tables, check constraints, delete tables, explain plans, lock tables, and repair tables.

28. What are the different languages present in DBMS?

The different languages include DDL (Data Definition Language), DML (Data Manipulation Language), TCL (Transaction Control Language), and DCL (Data Control Language).

29. What are ARIES in DBMS?

ARIES stands for Advanced Recovery by Indexed Sequential Execution. This feature helps to improve performance by avoiding full table scans when data is altered.

30. What is OLTP?

OLTP stands for Online Transaction Processing and is a technique used by databases to process transactions in real-time. It manages the applications which are oriented toward transactions and support online transactions.

31. What is DDL?

Data Definition Language (DDL) defines and structures data within a database, such as a relationship between tables and the definition of schema objects.

32. What is DML?

Data Manipulation Language (DML) is a language designed to extract, update and insert data. It is part of the relational database management system that provides users with access to the data. It mostly exists as a small part of a larger database language such as SQL in the form of some small operators.

33. What is DCL?

Data Control Language (DCL) defines who has access to which database objects. It includes commands like ‘revoke’, ‘grant’, etc., and tackles the permissions or rights given by the database to certain users.

34. What are the phases in Data Warehousing?

The phases of a data warehouse project include analysis, design, implementation, and usage.

35. What is RDBMS?

RDBMS stands for Relational Database Management System and uses the relational data model. It utilizes rows in tables to showcase data and ensures that the data remains secure, efficient, and accurate.

36. What is OLAP?

OLAP stands for Online Analytical Processing, which refers to tools that enable users to analyze multidimensional data through queries and aggregations.

37. What are the advantages of OLAP?

OLAP tools offer advantages such as data summarization, fast query response times, and the ability to relate different types of data.

38. What is MDX?

MDX stands for Multi-Dimensional eXpressions and is Microsoft's implementation of OLAP language.

39. What are the advantages of RDBMS?

At first glance, it is easy to note that RDBMS provides easy understandability for the end consumers as it is presented in a row-based table format. It also provides flexibility and efficiency of time as once updated in one table, RDBMS allows updation in all the related tables too. It allows users to view the data with their own interpretations and logic and also maintains the integrity of the data simultaneously.

40.  What do you understand by query optimization?

Optimizing queries is the process of creating queries that are as efficient as possible, given various technical constraints.

41. What are the components of a DBMS?

The components of a DBMS include client-server architecture, backup and recovery, concurrency control, security, and query optimization.

42. How can you connect to a DBMS using JDBC?

JDBC is a Java-specific API, which provides a way to connect to a DBMS from the Java Virtual Machine.

43. What do you understand by ‘Database Triggers’?

Database triggers are stored procedures that are automatically executed in response to some event on the database.

44. How can you insert data into a table?

You can insert data into a table using either an INSERT statement or the SQL LOAD command.

45. How would you define Triggers when talking to a non-DBA?

Triggers are used to automatically perform certain actions in response to changes in the database, such as updating dependent records or sending emails.

46. How would you define Triggers when talking to a DBA?

Triggers are stored procedures that are automatically executed in response to certain events on the database, such as updating dependent records or sending emails.

47. What are the different types of Database Locks?

The three types of database locks are share mode, update mode, and exclusive mode.

48. What are the advantages of locking Databases?

The major advantage of locking databases is ensuring the integrity of the data. Once locked by one process, the database cannot be meddled with through any other process. The ACID properties of transacting processes (as discussed above) necessarily require locking of the database to facilitate the process.

49. What is a view in a DBMS?

A view is like a virtual table that is composed of data from one or more base tables in the database.

50. What is an Entity-Relationship Model?

An entity-relationship (ER) model is a pictorial representation of data in a system, showing entities and the relationships between them.

Conclusion

DBMS Interview Questions are an important bit of knowledge for a candidate who is willing to go to a database programming company. In this article, we have created a list of 50 DBMS questions. We hope that this article is useful to those who need it and now they can give a good presentation at the interview stage. If you’re interested in learning more, check out Board Infinity’s course on Data Science!


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