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
271
The logical design of the database, which describes the data, relationships, and constraints, is called the:
Answer:
Conceptual Schema
The conceptual schema, also known as the logical schema, provides a high-level description of the entire database. It defines the structure, entities, relationships, and constraints for the whole organization.
272
The `INSERT`, `UPDATE`, and `DELETE` commands are all part of which SQL sub-language?
Answer:
DML
These three commands are the core of the Data Manipulation Language (DML), as they are used to add, modify, and remove data from database tables.
273
A 'deletion anomaly' is when:
Answer:
Deleting a row causes other, unrelated information to be lost.
A deletion anomaly occurs when the deletion of a set of data about one entity inadvertently causes the loss of data about a completely different entity. For example, if deleting the last student enrolled in a course also deletes the course information itself.
274
Which normal form is often considered sufficient for most practical database designs?
Answer:
3NF
For the majority of business applications, achieving Third Normal Form (3NF) provides an optimal balance between reducing data redundancy, preventing anomalies, and avoiding the complexity of higher normal forms. BCNF is also common, but 3NF is a widely accepted standard.
275
A table is in First Normal Form (1NF) if:
Answer:
It has no repeating groups or multi-valued attributes.
The core rule for 1NF is that every column in a table must hold atomic (indivisible) values, and each row must be unique. This means no multi-valued attributes, such as a single 'PhoneNumber' column containing multiple phone numbers.
276
The ability of a DBMS to enforce rules, such as ensuring an 'age' column only contains positive numbers, is called:
Answer:
Data Integrity
Data integrity refers to the maintenance of, and the assurance of the accuracy and consistency of, data over its entire life-cycle. A DBMS enforces integrity through constraints.
277
Which of the following is NOT a component of the Entity-Relationship model?
Answer:
Method
Methods, which represent behavior or operations, are a concept from the object-oriented data model, not the ER model. The ER model focuses on the static structure of data through entities, attributes, and relationships.
278
Which normal form is considered the strictest?
Answer:
Boyce-Codd Normal Form (BCNF)
Boyce-Codd Normal Form (BCNF) is an extension and a stricter version of 3NF. For a table to be in BCNF, for every non-trivial functional dependency X → Y, X must be a superkey. This handles certain rare anomalies that 3NF does not.
279
In a three-tier database architecture, which layer contains the business logic?
Answer:
Application tier
The three-tier architecture consists of a presentation tier (UI), an application tier (business logic), and a data tier (database). The application tier acts as a mediator, processing client requests and handling business rules before interacting with the database.
280
A relational database was first proposed by:
Answer:
E.F. Codd
Edgar F. Codd of IBM published the paper "A Relational Model of Data for Large Shared Data Banks" in 1970, which became the foundation for the relational database model.