Computer Science/IT MCQs
Topic Notes: Computer Science/IT
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
71
The `SELECT` statement, used for retrieving data from a database, is part of which SQL sub-language?
Answer:
Data Manipulation Language (DML)
DML consists of commands that deal with the manipulation of data present in the database. The `SELECT` statement is used to retrieve data, making it a core part of DML.
72
Which hardware component is most crucial for DBMS operation?
Answer:
High speed, large capacity disk
The performance of a Database Management System is heavily dependent on the speed and capacity of its storage. A high-speed, large-capacity disk is essential for quickly reading and writing the vast amounts of data that databases typically manage.
73
What is the cardinality of a relationship?
Answer:
The number of entity instances to which another entity instance can be associated.
Cardinality specifies the number of instances of one entity that can be related to the number of instances of another entity. Common cardinalities are one-to-one (1:1), one-to-many (1:N), and many-to-many (M:N).
74
The constraint that ensures that the value in a foreign key column must match an existing value in the primary key column of the related table is called:
Answer:
Referential Integrity
Referential integrity is a rule that ensures relationships between tables remain consistent. It prevents users from adding records to a related table if there's no associated record in the primary table, and it also restricts actions like deleting or changing a primary key that is being referenced.
75
Fourth Normal Form (4NF) is a level of database normalization that is concerned with eliminating a type of dependency known as:
Answer:
Multivalued Dependencies
4NF addresses multivalued dependencies. A multivalued dependency exists when the presence of one row in a table implies the presence of one or more other rows in that same table.
76
Which of the following statements does NOT accurately describe a benefit of utilizing a database management system (DBMS) for data organization?
Answer:
Automatically preserving all historical versions of deleted data for later retrieval.
The database approach offers several significant advantages in data management. Option A (minimizing redundant data and improving consistency) is a core benefit, as DBMSs are designed to reduce duplicative storage and maintain a single source of truth. Option C (enhanced security) is also a major advantage, as DBMSs provide mechanisms for access control, encryption, and data integrity checks. Option D (program/data independence) is crucial, meaning changes to the database schema or storage methods do not necessitate changes to the application programs accessing the data, and vice-versa.
Option B, 'Automatically preserving all historical versions of deleted data for later retrieval,' is NOT an inherent or primary advantage of the database approach itself. While some advanced database systems or specific configurations (like transaction logs, backup systems, or temporal databases) might offer robust recovery or versioning capabilities, the general 'database approach' does not *automatically* preserve deleted data in a readily 'associable' manner. Typically, once data is deleted, it is removed, and its retrieval would depend on backups or specific auditing features, not a default characteristic of the approach.
77
The term 'degree' of a relationship refers to:
Answer:
The number of participating entity types.
The degree of a relationship is the number of entity sets that participate in it. A relationship with two entity sets is binary (degree 2), one with three is ternary (degree 3), and so on.
78
The constraint that ensures all values in a column or a group of columns are different from one another is the:
Answer:
UNIQUE constraint
A `UNIQUE` constraint ensures that all values in a column are distinct. Unlike a primary key, a unique constraint can allow one NULL value.
79
Which of the following is an advantage of a DBMS over a traditional file system?
Answer:
Improved data sharing and security
A DBMS provides a centralized and controlled environment, which facilitates better data sharing among users and applications. It also offers robust security mechanisms to control access to data, which is a significant drawback of file systems.
80
A file produced by a spreadsheet:
Answer:
Is generally stored on disk in an ASCII text format
Spreadsheet applications often save files in standard formats like ASCII text or CSV (Comma-Separated Values). This makes the data accessible and easily importable by other programs, including database management systems.