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
4741
What does a double ellipse represent in an ER diagram?
Answer:
A multivalued attribute
A double ellipse is used to denote a multivalued attribute, which is an attribute that can hold multiple values for a single entity instance. For example, a `PhoneNumber` attribute for a person who has multiple phone numbers.
4742
Any candidate key that is not selected to be the primary key is referred to as a(n):
Answer:
Alternate Key
Alternate keys are the candidate keys that were not chosen as the primary key. They still uniquely identify records but are considered secondary identifiers.
4743
What does TCL stand for in the context of SQL?
Answer:
Transaction Control Language
TCL stands for Transaction Control Language. It includes commands like `COMMIT`, `ROLLBACK`, and `SAVEPOINT` to manage database transactions.
4744
The concept of 'inheritance' is a feature of which data model?
Answer:
Object-Oriented Model
Inheritance is a core principle of object-oriented programming and is carried over into the object-oriented data model. It allows a new class (subclass) to be based on an existing class (superclass), inheriting its attributes and methods.
4745
Which data model is known for its structural rigidity and data access being limited to predefined paths?
Answer:
Hierarchical model
The hierarchical model's tree-like structure is very rigid. To access data, you must traverse the tree from the root down through the parent-child paths, making access inflexible if the query doesn't match the predefined structure.
4746
Which model is not formal enough to be implemented directly in a programming language?
Answer:
ER model
The Entity-Relationship (ER) model is a high-level conceptual data model used for database design, which must be mapped to a logical model (like the relational model) before implementation.
4747
Which model is used to define a database?
Answer:
E-R diagram
An Entity-Relationship (E-R) diagram is used to visually represent the entities, attributes, and relationships within a database structure.
4748
Which data model extended the hierarchical model by allowing a record to have more than one parent, forming a graph-like structure?
Answer:
Network Model
The network model is an extension of the hierarchical model. It allows many-to-many relationships, meaning a child record can have multiple parent records, which creates a more flexible, graph-like structure.
4749
A relation is in Second Normal Form (2NF) if it is in 1NF and:
Answer:
All non-key attributes are fully functionally dependent on the primary key.
2NF addresses the issue of partial dependency. For a table to be in 2NF, it must first be in 1NF, and every non-prime attribute must depend on the entire primary key, not just a part of it (in the case of a composite primary key).
4750
Which of the following is a DDL command?
Answer:
CREATE
DDL stands for Data Definition Language. Its commands are used to define or modify the database schema. CREATE is a DDL command used to create new database objects like tables, indexes, or views.