Which SQL command is used to modify existing records within a database table?
Correct answer: D
The UPDATE command modifies the values of existing records in a database table.
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Which SQL command is used to remove existing records from a database table?
Correct answer: A
The DELETE command removes existing records from a database table.
Which SQL command is used to create a new table structure within a database?
Correct answer: A
The CREATE TABLE command defines and creates a new table structure in a database.
Which SQL command is used to permanently remove an entire table, including its structure and data, from a database?
Correct answer: A
The DROP TABLE command permanently deletes a table, along with its structure and all its data.
Which SQL command is used to modify the structure of an existing table, such as adding or removing a column?
Correct answer: C
The ALTER TABLE command modifies an existing table's structure, such as adding, changing, or dropping columns.
Which database key uniquely identifies each record within a table and cannot contain duplicate or null values?
Correct answer: A
A primary key uniquely identifies each record in a table and must be unique and non-null.
Which database key is a field in one table that references the primary key of another table, establishing a relationship between them?
Correct answer: A
A foreign key links two tables together by referencing the primary key of another table.
Which database key refers to a column, or combination of columns, that could qualify as a unique identifier for a table's records?
Correct answer: B
A candidate key is any column (or set of columns) that could uniquely identify records, from which a primary key is chosen.
Which database key is formed by combining two or more columns to uniquely identify a record, when no single column suffices?
Correct answer: D
A composite key uses a combination of multiple columns together to uniquely identify a record.
What is the process of organizing a database's tables and columns to minimize data redundancy and improve data integrity called?
Correct answer: B
Normalization organizes database structure to reduce redundancy and maintain data integrity.
What is the process of intentionally introducing redundancy into a database, often to improve read performance, called?
Correct answer: B
Denormalization deliberately adds redundancy to a database, typically to improve query performance.
What database structure improves the speed of data retrieval operations at the cost of additional storage and update overhead?
Correct answer: C
An index improves data retrieval speed by allowing the database to find records more quickly, at some storage/update cost.
What term describes a virtual table in a database, generated from a stored SQL query, that does not itself store data physically?
Correct answer: A
A view is a virtual table based on a stored query; it doesn't store data itself but presents data from underlying tables.
What database object automatically executes a predefined action in response to specific events, like an insert or update?
Correct answer: C
A trigger automatically executes a defined action in response to specific database events, such as inserts or updates.
What overall term describes the structural design of a database, including its tables, fields, and relationships?
Correct answer: D
A schema defines the overall structural blueprint of a database, including its tables, fields, and relationships.
What does the acronym 'ACID', describing key database transaction properties, stand for?
Correct answer: C
ACID stands for Atomicity, Consistency, Isolation, and Durability — the properties ensuring reliable database transactions.
Which ACID property ensures that a database transaction is treated as a single, indivisible unit that either fully completes or fully fails?
Correct answer: C
Atomicity ensures a transaction is all-or-nothing — it either completes entirely or has no effect at all.
Which ACID property ensures that a database transitions from one valid state to another, maintaining all defined rules and constraints?
Correct answer: A
Consistency ensures a transaction brings the database from one valid state to another, respecting all rules and constraints.
Which ACID property ensures that concurrently executing transactions do not interfere with or affect each other's outcomes?
Correct answer: B
Isolation ensures that concurrent transactions execute independently, without unintended interference between them.
Which ACID property ensures that once a transaction is committed, its changes are permanently saved even in the event of a system failure?
Correct answer: D
Durability guarantees that committed transaction changes persist permanently, even after a system crash or failure.
Which category of database management systems is designed for flexible, non-tabular data storage, often used for large-scale, unstructured data?
Correct answer: D
NoSQL databases offer flexible, non-relational data storage models suited to large-scale or unstructured data.
Which type of NoSQL database stores data as flexible, JSON-like documents, such as MongoDB?
Correct answer: B
Document databases, like MongoDB, store data as flexible, JSON-like documents rather than rigid tables.
Which type of NoSQL database stores data simply as pairs of unique keys and corresponding values, such as Redis?
Correct answer: B
Key-value stores, like Redis, organize data as simple pairs of unique keys and their associated values.
Which type of NoSQL database organizes data into columns rather than rows, optimized for handling very large datasets, such as Cassandra?
Correct answer: C
Column-family stores, like Cassandra, organize data by columns, optimized for scalability across large datasets.
Which type of NoSQL database is specifically designed to store and query data based on relationships between entities, such as Neo4j?
Correct answer: C
Graph databases, like Neo4j, are optimized for storing and querying complex relationships between data entities.