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
181
The concept of "many-to-many" relationships, where an entity can be related to multiple other entities and vice-versa, is most directly supported by which data model?
Answer:
Network Model
The network model was specifically designed to overcome the limitations of the hierarchical model, and its primary advantage was its natural ability to model complex many-to-many relationships through its graph-like structure.
182
An attribute that can be broken down into smaller sub-parts is known as a:
Answer:
Composite attribute
A composite attribute is an attribute that can be subdivided into smaller, meaningful components. For instance, an `Address` attribute can be broken down into `Street`, `City`, and `ZipCode`.
183
What is a foreign key?
Answer:
A key that is used to link two tables together.
A foreign key is a key used to link two tables together. It is a field (or collection of fields) in one table that refers to the PRIMARY KEY in another table. This establishes referential integrity between the two tables.
184
To modify data in an existing row, you should use the:
Answer:
`UPDATE` statement
The `UPDATE` statement is a DML command specifically used to modify existing records in a table. `ALTER` is for changing the table's structure.
185
Which of the following represents the 'Consistency' property in ACID?
Answer:
The database must be in a valid state before and after the transaction.
Consistency ensures that any transaction will bring the database from one valid state to another. It prevents data corruption by ensuring that all integrity constraints are maintained.
186
A record management system:
Answer:
Can be used to extract information stored in a computer file
The core function of a record management system is to provide the tools to effectively manage and extract specific pieces of information that are stored within a computer file or a set of files.
187
If a foreign key constraint does not specify an `ON DELETE` or `ON UPDATE` action, what is the default behavior?
Answer:
NO ACTION / RESTRICT
The default behavior in most SQL databases is `NO ACTION` or `RESTRICT`. This means that any `DELETE` or `UPDATE` operation on a primary key in the parent table will fail if there are dependent rows in the child table.
188
GUID is a 128-bit number used for unique data identification. What does it stand for?
Answer:
Globally Unique Identifier
A GUID ensures that database entries or software components have unique references. [cite: 245, 246]
189
In an ER diagram, a diamond shape represents a(n):
Answer:
Relationship set
A diamond shape is the standard symbol used in ER diagrams to represent a relationship set, which describes the association among several entities.
190
In a database field, which property ensures it cannot be left blank?
Answer:
Required
The Required property (often implemented as a NOT NULL constraint) ensures that a field must contain a value and cannot be left empty.