DBMS Interview Questions (2025)
Check the list of DBMS interview questions for different topics like definitions, basic SQL queries, transactions, performance tuning, and advanced topics, which will help you prepare well for interviews. This will be useful for beginners and seasoned people.
What is DBMS?
A Database Management System (DBMS) is a software application that interacts with users, applications, and the database itself to capture and analyze data. It allows for the creation, retrieval, updating, and management of data efficiently.
Why DBMS is Important from a Placements Perspective
Having a strong grip on DBMS is one of the keys to cracking technical interviews and securing dream placements in the software development, data, and IT sectors. Here's why it should be a priority for you:
- Great Demand: The majority of firms require professionals who can effectively manage and analyze data, making DBMS knowledge a significant advantage.
- Fundamental Concept: DBMS is the foundation of data management, and many technical interviews for various roles include questions related to data management concepts.
- Real-World Application: Proficiency in DBMS tools and concepts such as SQL, normalization, and transactions demonstrates your ability to solve real-world problems.
- Versatility: DBMS knowledge is applicable across a variety of industries, including database administration, backend development, and data engineering.
- Data Structure: Understanding DBMS enhances your grasp on data structures and their application, which is crucial for building efficient and scalable systems.
Complete DBMS & SQL Free resources
Basic DBMS Interview Questions
1. What is DBMS?
2. What is a database?
3. What is a database system?
4. What are the advantages of DBMS over traditional file-based systems?
5. Explain the difference between DBMS and RDBMS.
6. What is a database schema?
7. What is normalization, and why is it used?
8. What are the different types of keys in DBMS?
9. Explain primary key, foreign key, and unique key.
10. What is a composite key?
11. What is a surrogate key?
12. What is a candidate key?
13. What is the difference between a super key and a candidate key?
14. What is a relationship in DBMS, and what are the types of relationships?
15. What is an entity in DBMS?
16. What is an attribute in DBMS?
17. What is a tuple in DBMS?
18. What is the difference between primary key and unique constraints?
19. What is the purpose of normalization in DBMS?
20. What is the difference between a database schema and a database state?
21. What is the concept of sub-query in terms of SQL?
22. What is the use of the DROP command, and what are the differences between DROP, TRUNCATE, and DELETE commands?
23. What is the main difference between UNION and UNION ALL?
24. What is Correlated Subquery in DBMS?
25. Explain Entity, Entity Type, and Entity Set in DBMS.
26. What are the different levels of abstraction in the DBMS?
27. What integrity rules exist in the DBMS?
28. What is the E-R model in DBMS?
29. What is a functional dependency in DBMS?
30. What is 1NF in DBMS?
31. What is 2NF in DBMS?
32. What is 3NF in DBMS?
33. What is BCNF in DBMS?
34. What is a CLAUSE in SQL?
35. What is the difference between a database and a schema?
36. What is the purpose of SQL?
37. What are the main differences between Primary Key and Unique Key?
38. What is the difference between a database and a filesystem?
39. What is the purpose of the CASE statement in SQL?
40. What is the difference between a database and a blockchain?
SQL Queries
41. What is SQL?
42. Explain the difference between DDL, DML, and DCL.
43. What is the difference between DELETE and TRUNCATE?
44. What is the difference between WHERE and HAVING?
45. What is a JOIN? Explain different types of JOINs.
46. What is a subquery?
47. What is a view in SQL? How to create a view?
48. What are the uses of a view?
49. What is an index? Explain different types of indexes.
50. What is a stored procedure?
51. What is a trigger?
52. What is the difference between UNION and UNION ALL?
53. What is the difference between INNER JOIN and OUTER JOIN?
54. What is a self-join?
55. What is a correlated subquery?
56. What is the difference between GROUP BY and ORDER BY?
57. What is the purpose of the DISTINCT keyword?
58. What is the difference between CHAR and VARCHAR data types?
59. What is the purpose of the LIMIT clause?
60. What is the difference between a database and a table?
61. What is the purpose of the EXISTS clause?
62. How to print duplicate rows in a table?
63. What is Identity?
64. What is the difference between Trigger and Stored Procedure?
65. What is the purpose of the WITH clause in SQL?
66. How can you get the alternate records from the table in SQL?
67. How is pattern matching done in SQL?
68. What are the different types of joins in SQL?
69. What is the difference between HAVING and WHERE clauses?
70. What is the purpose of the DROP command?
Transactions and Concurrency
71. What is a transaction?
72. Explain ACID properties.
73. What is a deadlock?
74. What is concurrency control?
75. Explain the difference between optimistic and pessimistic locking.
76. What is a rollback?
77. What is a savepoint?
78. What is the difference between a transaction and a batch?
79. What is a dirty read in DBMS?
80. What is a phantom read in DBMS?
81. What is a non-repeatable read in DBMS?
82. What is two-phase locking (2PL)?
83. What is the difference between serializable and repeatable read isolation levels?
84. What is a log file in DBMS?
85. What is the purpose of the COMMIT statement?
86. What is a Live Lock?
87. What is the difference between a shared lock and an exclusive lock?
Advanced DBMS Concepts
88. What is database partitioning?
89. What is database sharding?
90. Explain CAP theorem.
91. What is NoSQL?
92. Explain the difference between SQL and NoSQL.
93. What is a distributed database?
94. What is database replication?
95. What is a materialized view?
96. What is database indexing, and how does it work?
97. What is a B-tree index?
98. What is a hash index?
99. What is the difference between horizontal and vertical partitioning?
100. What is a database cluster?
101. What is a database trigger, and how is it different from a stored procedure?
102. What is a cursor in DBMS?
103. What is Denormalization?
104. What is QBE (Query By Example)?
105. Why are cursors necessary in embedded SQL?
106. What is the main goal of RAID technology?
107. What is a checkpoint in DBMS?
108. When does a checkpoint occur in DBMS?
109. What do you mean by transparent DBMS?
110. What are the unary operations in Relational Algebra?
111. What is Relational Algebra?
112. What is Relational Calculus?
113. What do you understand by query optimization?
114. What do you mean by durability in DBMS?
115. What is System R? How many of its two major subsystems?
116. What is Data Independence?
117. What are the three levels of data abstraction?
Performance Tuning
118. How do you optimize a SQL query?
119. What is a query execution plan?
120. What are the common performance issues in databases?
121. How do you handle slow-running queries?
122. What is database caching?
123. What is the difference between a clustered and a non-clustered index?
124. What is query optimization?
125. What is the purpose of indexing in databases?
126. How do you identify and resolve deadlocks?
127. What is the role of the database buffer pool?
Security
128. What is database security?
129. What is SQL injection?
130. How do you prevent SQL injection?
131. What is database encryption?
132. What is role-based access control?
133. What is the difference between authentication and authorization?
134. What is database auditing?
135. What is data masking?
136. What is a firewall in the context of database security?
137. What is the purpose of SSL/TLS in database connections?
Miscellaneous
138. What is a data warehouse?
139. What is OLAP and OLTP?
140. Explain the difference between a data lake and a data warehouse.
141. What is ETL?
142. What is a database trigger?
143. What is the difference between a database and a data warehouse?
144. What is the purpose of a data dictionary?
145. What is the difference between a fact table and a dimension table?
146. What is a star schema?
147. What is a snowflake schema?
148. What is the purpose of the WITH clause in SQL?
149. What is the difference between a database and a blockchain?
150. What is the difference between logical database design and physical database design?
151. What are temporary tables? When are they useful?
152. Explain different types of failures that occur in the Oracle database.
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