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
21
To ensure the key in one table matches a key in another, you must establish:
Answer:
Referential integrity
Referential integrity is a set of rules that ensures relationships between records in related tables are valid and consistent.
22
A CHECK constraint is used to enforce:
Answer:
Domain integrity
A CHECK constraint enforces domain integrity by ensuring that all values in a column satisfy a certain condition or logical expression. For example, `CHECK (Age >= 18)`.
23
Primitive operations common to all record management systems include:
Answer:
All of above
All record management systems, regardless of their complexity, provide a set of fundamental or primitive operations. These universally include the ability to look-up (search for) data, sort data into a specific order, and print or display the data.
24
In the terminology of the relational model, a single column of a table is also known as a(n):
Answer:
Attribute
In the formal relational model, a column is called an attribute. It represents a specific property or characteristic of the entity described by the table.
25
Which of these is a potential disadvantage of a highly normalized database?
Answer:
Slower query performance due to more table joins
In a highly normalized database (e.g., 3NF or BCNF), information is spread across many small tables. Retrieving comprehensive data often requires joining multiple tables, which can be computationally expensive and lead to slower query performance compared to a denormalized structure.
26
A functional dependency X -> Y means that:
Answer:
The value of Y depends on the value of X.
The notation X -> Y represents a functional dependency, which means that the value of attribute(s) X uniquely determines the value of attribute(s) Y. For any given value of X, there will be only one corresponding value of Y.
27
Which part of a database stores details about the data itself?
Answer:
Data dictionary
A data dictionary contains metadata, which describes the structure, constraints, and properties of the data stored in the database.
28
A table containing a column like 'Hobbies' where a single cell can contain multiple values (e.g., "Reading, Hiking, Swimming") violates which normal form?
Answer:
First Normal Form (1NF)
The presence of a multi-valued attribute like 'Hobbies' violates the atomicity rule of 1NF. To be in 1NF, this should be broken down into separate rows or a separate table.
29
The `SET DEFAULT` referential action will:
Answer:
Set the foreign key in child rows to its predefined default value.
If a record in the parent table is deleted or updated, the `SET DEFAULT` action will set the foreign key columns in the corresponding child table records to the default value defined for those columns.
30
What is the function of `TRUNCATE TABLE`?
Answer:
To delete all data from a table quickly.
`TRUNCATE TABLE` is a DDL command that removes all rows from a table, but the table structure, columns, constraints, and indexes remain. It is generally much faster than a `DELETE` statement with no `WHERE` clause.