In database management systems, the collection of data stored in a database at a particular point of time is referred to by which term?

Introduction / Context:
Database theory distinguishes between the logical design of a database and the actual data that is present at any given time. Understanding this distinction is important for discussing concepts such as schema evolution, snapshots, and queries. This question tests whether learners know the term used for the set of data values currently stored in a database at a specific moment.

Given Data / Assumptions:

• The question refers to the state of data in a database at a particular point in time.
• Options include Intension, Extension, Back up, Application, and a general distractor.
• We assume familiarity with basic database terminology such as schema and instance.
• We focus on the conceptual meaning rather than on implementation details.

Concept / Approach:
In database terminology, the intension of a database refers to its schema, that is, the set of definitions that describe tables, fields, and relationships. The extension, also called the database instance, refers to the actual set of tuples or records stored in the database at a particular time. A backup is a copy of data for recovery purposes and is not a conceptual term of the data model. An application is software that uses the database but is not the database content itself. The approach is to match the definition given in the question with the correct theoretical term, which is extension.

Step-by-Step Solution:
Step 1: Recall that a database schema or intension describes the structure, including table names, column names, and data types.Step 2: Understand that the actual rows of data present in the tables at a certain moment are called the extension or instance of the database.Step 3: Recognise that the question speaks about data at a particular point of time, not about the structural design.Step 4: Compare this with the options and identify Extension as the term that matches this concept.Step 5: Conclude that Extension is the correct answer.

Verification / Alternative Check:
To verify, consider a simple example of a Student table with columns such as RollNumber and Name. The intension is the definition of this table and its columns, which usually remains stable over many operations. The extension is the set of student rows currently stored, which changes as students are added, updated, or removed. If you take a snapshot of the table at 10:00 AM and another at 3:00 PM, the schema is the same but the extension may differ, clearly showing that the term refers to the state of data at a given time.

Why Other Options Are Wrong:
Intension refers to the schema or structural definition, not to the instantaneous data. Back up is a copy of the database used for recovery and does not represent the theoretical state at a specific moment in normal operation. Application is the program that interacts with the database and may display or change data, but it is not the data itself. None of these is incorrect because Extension is the specific theoretical term requested.

Common Pitfalls:
Students may confuse intension and extension because the words sound similar and are sometimes introduced together without enough examples. Others might choose Back up, thinking of a stored copy of data at a particular time, which feels similar to a snapshot. However, a backup is a practical file or set of files, not a theoretical notion in the data model. Remembering that intension equals schema and extension equals current data instance helps overcome this confusion.

Final Answer:
In database management systems, the collection of data stored at a particular point of time is called the Extension of the database.