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
4881
Before a table can be in 2NF, it must first be in:
Answer:
1NF
The normal forms are progressive. A table must satisfy the rules of First Normal Form (1NF) before it can be considered for Second Normal Form (2NF).
4882
Which command is used to add, delete, or modify columns in an existing table?
Answer:
`ALTER TABLE`
The `ALTER TABLE` command is a DDL statement used to change the structure of an existing table, such as adding a column, dropping a column, or changing a column's data type.
4883
Which key uniquely identifies database records without referring to other data?
Answer:
Candidate Key
A candidate key can uniquely identify rows in a table; [cite: 300] [cite_start]one of them is chosen as the primary key. [cite: 301]
4884
A key characteristic of a database system is that the data is integrated and:
Answer:
Shared
A fundamental principle of the database approach is that data is a shared resource. It is integrated into a single repository that can be accessed by many different users and applications throughout an organization.
4885
The model for a record management system might be:
Answer:
All of above
A record management system is designed to digitally replicate real-world methods of organizing information. Therefore, its logical model could be based on simple structures like a handwritten list, a Rolodex, or a more complex business form.
4886
Which SQL keyword is used to sort the result-set of a query in ascending or descending order?
Answer:
`ORDER BY`
The `ORDER BY` clause is used to sort the records in the result set. By default, it sorts in ascending order (`ASC`), but it can be specified to sort in descending order (`DESC`).
4887
Which data model uses the concept of 'owners' and 'members' to describe relationships?
Answer:
Network model
In the CODASYL network model, relationships (called sets) are defined between two record types: an 'owner' record type and a 'member' record type. This structure allows for the representation of many-to-many relationships.
4888
Which DCL command would a database administrator use to give a user permission to perform `SELECT` operations on a table?
Answer:
`GRANT SELECT ON table_name TO user;`
The `GRANT` command is the standard DCL statement used to provide specific privileges (like `SELECT`, `INSERT`, `UPDATE`, etc.) on database objects to users or roles.
4889
Which constraint ensures that all entries in a specific column must have a value and cannot be left empty?
Answer:
NOT NULL
The `NOT NULL` constraint enforces that a column cannot accept NULL values. This means that a value must be entered for that column when a new record is inserted or an existing record is updated.
4890
Which operator combines the result-set of two or more SELECT statements but removes duplicate rows?
Answer:
UNION
The `UNION` operator is used to combine the result sets of two or more SELECT statements. It returns all unique rows selected by each query. `UNION ALL` performs the same function but includes all duplicate rows.