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
201
An 'associative entity' is used to model which type of relationship?
Answer:
Many-to-many
In an ER model, a many-to-many (M:N) relationship is often implemented by creating a new entity called an associative entity (or bridge table). This entity holds the primary keys of the two related entities as foreign keys.
202
What is the language used by most of the DBMSs for helping their users to access data?
Answer:
Query Language
A Query Language is a specialized computer language used to make queries (requests for information) from a database. While SQL is the most common example, the general category of language used for this purpose is a query language.
203
What is the fundamental building block of data in the relational model?
Answer:
The Relation (Table)
The entire relational model is built upon the mathematical concept of a "relation," which is implemented as a table. Tables are the only data structure used to store and manipulate data.
204
The process of intentionally introducing redundancy into a normalized database to improve query performance is known as:
Answer:
Denormalization
Denormalization is a strategy used to increase the performance of a database by adding redundant data. It aims to reduce the number of joins required for a query, which can speed up data retrieval at the cost of some data integrity risk.
205
The Object-Oriented Data Model represents both data and its relationships in a single structure known as a(n):
Answer:
Object
In the Object-Oriented Data Model, information is represented in the form of objects, similar to object-oriented programming. Each object encapsulates both data (attributes) and the operations (methods) that can be performed on it.
206
A transaction begins with the first executable SQL statement and ends when it is explicitly:
Answer:
Committed or rolled back.
A transaction is a sequence of operations performed as a single logical unit of work. It is terminated by either a `COMMIT` (making changes permanent) or a `ROLLBACK` (undoing the changes).
207
The purpose of a `DEFAULT` constraint is to:
Answer:
Provide a value for a column when no value is specified during an insert.
The `DEFAULT` constraint is used to automatically assign a predefined value to a column if a user does not provide a value for it when inserting a new record.
208
The ability to change the conceptual schema without having to change external schemas or application programs is known as:
Answer:
Logical Data Independence
Logical data independence allows the logical structure of the database (the conceptual schema) to be modified without requiring changes to the application programs that access the database.
209
Which statement is used to remove a table completely from the database?
Answer:
`DROP TABLE table_name;`
The `DROP TABLE` statement is a DDL command that deletes the table's definition, all its data, indexes, triggers, constraints, and permission specifications. This action is permanent and cannot be rolled back.
210
Which of the following is true about a candidate key?
Answer:
It can be a primary key.
A table can have multiple keys that can uniquely identify a record; these are called candidate keys. The database administrator chooses one of these candidate keys to be the primary key for the table.