Quickly Complete DBMS Before Interview 2026
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Contents
Get The Basics Sorted
Q1. What is data, a database, and a DBMS?
Data is simply raw information. For example, a student’s name, age, and marks are all pieces of data.
A database is an organized collection of data that we can store, access, and manage efficiently.
A DBMS, or Database Management System, is software that helps us create and manage databases. It provides ways to read, insert, update, and delete data, while also handling things like access control, concurrent users, and recovery after failures.
Possible follow-up: What’s the difference between a database and a DBMS?
A database is the actual collection of data, while a DBMS is the software we use to manage that data.
For example, MySQL is a DBMS, and the data stored inside a MySQL database is our actual data.
Q2. What are the different types of databases?
There are different types of databases depending on how they organize and store data.
The most common ones are relational databases, which store data in tables, and NoSQL databases, which include document, key-value, wide-column, and graph databases.
We also have object-oriented databases, which store data as objects.
The choice depends on what we’re building and how we need to access our data.
Possible follow-up: What’s the difference between SQL and NoSQL databases?
Relational databases organize data into tables with predefined schemas and typically use SQL to query it.
NoSQL databases use different data models, such as documents or key-value pairs. They can be useful when the data structure or access patterns don’t fit naturally into relational tables.
Neither is universally better. It depends on the application’s requirements.
We generally use SQL databases when our data has clear relationships and we need things like transactions and data consistency. For example, in a banking application, transferring money between two accounts must be handled reliably, so a relational database like PostgreSQL or MySQL is a good choice.
NoSQL databases are useful when our data structure or access patterns fit better with a non-relational model. For example, a product catalog where different products have different attributes could work well with a document database like MongoDB.
Q3. Why do we need a DBMS? Why not just use files?We can store data in files, and for small applications, that might be perfectly fine.
But as an application grows, we need to handle multiple users accessing the same data, maintain data consistency, control who can access what, and recover data if something goes wrong.
A DBMS provides features to handle these problems in a more reliable and organized way.
It also gives applications a consistent interface for working with data instead of making every application implement its own storage and management logic.
Possible follow-up: Can we use CSV or JSON instead of a database?
Yes. If we’re storing a small amount of relatively simple data and don’t need concurrent updates or complex queries, CSV or JSON might be enough.
But when the application needs complex relationships, concurrent access, transactions, or reliable recovery, a DBMS is usually a better choice.
Possible follow-up: Should we store images and videos directly in a database?
We can, but in many applications, we store the actual files in object storage or a file system and keep their paths, URLs, and metadata in the database.
This can make file delivery and storage management more efficient. However, storing files directly in a database can also make sense when transactional consistency or centralized management is important.
DBMS Architectures (1, 2 and 3 Tier)
Q4. What is 1-tier architecture?
USER <—> DATABASE SYSTEM
In a 1-tier architecture, the application and database are present in the same system, and the user can interact with the database directly. It’s commonly associated with local development or standalone database applications.
Q5. What is 2-tier architecture?
USER and APPLICATION <—> DATABASE SYTEM
In a 2-tier architecture, the client application communicates directly with the database server. For example, a desktop application connecting directly to a MySQL database.
Q6. What is 3-tier architecture?
USER and APPLICATION <—> APPLICATION SERVER and DATABASE SYSTEM
In a 3-tier architecture, we have three layers: the presentation layer, the application layer, and the database layer.
The client sends a request to the application server, the application server processes it and communicates with the database, and the result is sent back to the client.
This is common in web applications because it separates the user interface, business logic, and data storage.
