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
61
A ___ is a descriptive label used to identify the type of content to be entered into a field.
Answer:
Field name
A field name is a unique identifier for a field (or column) within a database table.
62
Which key is a "minimal superkey"?
Answer:
Candidate Key
A superkey is any set of attributes that uniquely identifies a row. A candidate key is a superkey that is minimal, meaning no attribute can be removed from it without losing the unique identification property.
63
What is the expected result if you attempt to insert a record with a primary key value that already exists in the table?
Answer:
The operation will fail due to a constraint violation.
A primary key constraint enforces uniqueness for the specified column(s). Attempting to insert a duplicate value will violate this constraint, causing the database to reject the operation and return an error.
64
Which DML command is used to add new rows of data into a table?
Answer:
`INSERT INTO`
The `INSERT INTO` statement is the standard DML command used to insert one or more new records (rows) into a table.
65
In database management, which term refers to the collection of specific data stored within a database at a given instant?
Answer:
Extension
The 'extension' of a database, also known as the database state, represents the actual data values (the set of all rows or 'tuples' in all 'relations' or tables) present in the database at a precise moment in time. This is distinct from the 'intension' (or schema), which defines the database's structure, rules, and data types, independent of the actual data contained within it. The 'schema' is the blueprint, while the 'extension' is the populated building. A 'constraint' is a rule enforced on the data, not the data itself.
66
The overall process of structuring a relational database by organizing its columns and tables to minimize data redundancy is known as:
Answer:
Normalization
Normalization is the fundamental database design technique of creating a clean, logical data structure with minimal redundancy. It involves dividing larger tables into smaller, well-structured tables and defining relationships between them.
67
A relation is in 3NF if it is in 2NF and...
Answer:
has no transitive dependencies.
To be in Third Normal Form (3NF), a relation must first be in 2NF. Additionally, all its attributes must be dependent only on the primary key, meaning there are no transitive dependencies, where a non-key attribute depends on another non-key attribute.
68
A table is in Fourth Normal Form (4NF) if it is in BCNF and has no:
Answer:
Multi-valued dependencies
Fourth Normal Form (4NF) is concerned with multi-valued dependencies. A table is in 4NF if it is in Boyce-Codd Normal Form (BCNF) and does not have any non-trivial multi-valued dependencies.
69
Why might a database designer choose to denormalize a database?
Answer:
To improve query performance.
The primary motivation for denormalization is to boost query performance. By reducing the number of joins required to retrieve data, the database can respond to read requests much faster, which is critical for read-heavy applications.
70
What is a 'schema' in the context of a database?
Answer:
The overall design or structure of the database.
A database schema is the blueprint of the database. It defines the tables, the fields in each table, the relationships between fields and tables, and the constraints. It describes the structure but not the data itself.