Computer Science - IT MCQs
Topic Notes: Computer Science - IT
<p>MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.</p>
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
441
A relation is in BCNF if and only if every determinant is a:
Answer:
Candidate key (or superkey)
The formal definition of Boyce-Codd Normal Form (BCNF) is that for every non-trivial functional dependency X → Y in a table, X must be a superkey (which means it's a candidate key or contains a candidate key).
442
Which of the following is NOT a type of data anomaly that normalization helps to prevent?
Answer:
Concurrency Anomaly
Update, Insertion, and Deletion anomalies are problems related to data redundancy that are addressed by normalization. Concurrency anomalies are issues that arise from multiple simultaneous transactions and are managed by the DBMS's concurrency control mechanisms, not by normalization.
443
Which of the following is true of a network structure?
Answer:
It allows a many-to-many relationship
Unlike the hierarchical model, the network data model is more flexible. It represents relationships as a graph, allowing a record to have multiple "parent" records, which effectively supports the modeling of complex many-to-many relationships between data entities.
444
Which SQL statement is used to update data in a database?
Answer:
UPDATE
The UPDATE statement is the standard SQL command used to modify existing records in a table. You use a WHERE clause to specify which record(s) should be updated.
445
Denormalization is most beneficial in which type of system?
Answer:
Read-heavy systems like data warehouses
Denormalization is a technique used to optimize the read performance of a database. It is most suitable for systems where data is read far more frequently than it is written, such as in data warehousing and business intelligence applications.
446
The main purpose of a primary key in a database is to:
Answer:
Uniquely identify a record
The primary key ensures that each record in a table is distinct and can be uniquely identified.
447
Accessing data by navigating through a series of pointers or links from one record to another is a characteristic of which data models?
Answer:
Hierarchical and Network Models
Both the hierarchical and network models are considered navigational databases. To retrieve data, an application program must traverse a path through the data structure using predefined links or pointers.
448
What does the acronym DBMS stand for?
Answer:
Database Management System
DBMS stands for Database Management System. It is the software that interacts with end-users, applications, and the database itself to capture and analyze the data.
449
To sort the results of a query in descending order, which keyword should be used with `ORDER BY`?
Answer:
DESC
The `DESC` keyword is used with the `ORDER BY` clause to sort the data in descending order (from highest to lowest). The default sorting order is ascending (`ASC`).
450
Data becomes __ when presented in a way people can understand and use.
Answer:
Information
Data is raw facts, while information is data that has been processed into a meaningful and useful context.