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
4871
A 'determinant' in a functional dependency (X → Y) is:
Answer:
The attribute that determines the other (X).
In the functional dependency X → Y, the attribute or set of attributes on the left side (X) is called the determinant, as its value determines the value of the attribute(s) on the right side (Y).
4872
The process of normalization was first proposed by:
Answer:
E.F. Codd
E.F. Codd, the creator of the relational model, also introduced the concept of normalization and defined the first three normal forms (1NF, 2NF, 3NF) to solve the problem of data anomalies.
4873
A __, or data file, is a collection of related records.
Answer:
Table
A table in a relational database is a collection of related data entries and it consists of columns and rows. It is also known as a data file.
4874
In an ER diagram, a double rectangle represents a(n):
Answer:
Weak entity set
A weak entity set, which depends on a strong entity set for its existence and primary key, is represented by a double-lined rectangle.
4875
A query within another query is called a:
Answer:
All of the above
All three terms—Nested Query, Subquery, and Inner Query—are used to describe a query that is embedded inside the `WHERE`, `HAVING`, `FROM`, or `SELECT` clause of another SQL query.
4876
Which of the following is NOT a type of constraint?
Answer:
ORDER BY
ORDER BY is a SQL clause used in a SELECT statement to sort the result set in ascending or descending order. It is used for data retrieval and presentation, not for enforcing rules on the data stored in the table like PRIMARY KEY, FOREIGN KEY, and UNIQUE constraints.
4877
A database table can have how many primary keys?
Answer:
Only one
By definition, a table can have only one primary key. However, this single primary key can be a composite key, meaning it can consist of multiple columns.
4878
What is a NOT NULL constraint?
Answer:
It ensures that a column must have a value.
The NOT NULL constraint enforces the rule that a column cannot accept NULL values. This means that a value must be provided for that column whenever a new record is inserted or an existing record is updated.
4879
A superkey is a:
Answer:
Set of one or more attributes that, taken collectively, allows us to identify uniquely an entity in the entity set.
A superkey is any combination of columns that uniquely identifies a row. A candidate key is a minimal superkey (i.e., a superkey from which no columns can be removed without losing the uniqueness property).
4880
The relational model, proposed by E.F. Codd, represents data and relationships among data as a collection of:
Answer:
Tables
The fundamental concept of the relational model is the relation, which is physically represented as a table. Data is stored in two-dimensional tables consisting of rows and columns.