Data Models into Database Designs
Q. In a relational database, what does a foreign key represent?
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A.
A unique identifier for a table
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B.
A reference to a primary key in another table
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C.
An attribute of an entity
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D.
A constraint on data types
Solution
A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table.
Correct Answer: B — A reference to a primary key in another table
Q. In a relational database, what is a foreign key?
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A.
A unique identifier for a record
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B.
A key that links two tables together
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C.
A key that is not indexed
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D.
A key used for data encryption
Solution
A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table, establishing a link between them.
Correct Answer: B — A key that links two tables together
Q. In an Entity-Relationship (ER) model, what does a diamond shape represent?
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A.
Entity
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B.
Attribute
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C.
Relationship
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D.
Weak entity
Solution
In an ER model, a diamond shape represents a relationship between entities.
Correct Answer: C — Relationship
Q. What does the term 'denormalization' refer to in database design?
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A.
The process of reducing redundancy
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B.
The process of increasing redundancy for performance
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C.
The process of normalizing data
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D.
The process of creating indexes
Solution
Denormalization refers to the process of increasing redundancy in a database to improve performance, often at the cost of data integrity.
Correct Answer: B — The process of increasing redundancy for performance
Q. What is a transaction in the context of a database management system?
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A.
A single SQL command
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B.
A sequence of operations treated as a single unit
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C.
A backup of the database
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D.
A method of data retrieval
Solution
A transaction is a sequence of operations that are treated as a single unit of work, ensuring data integrity.
Correct Answer: B — A sequence of operations treated as a single unit
Q. What is the main advantage of using indexing in a database?
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A.
Increases data redundancy
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B.
Improves data integrity
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C.
Speeds up data retrieval
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D.
Simplifies database design
Solution
Indexing improves data retrieval speed by allowing the database to find data more quickly.
Correct Answer: C — Speeds up data retrieval
Q. What is the primary purpose of normalization in database design?
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A.
To increase data redundancy
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B.
To eliminate data anomalies
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C.
To improve query performance
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D.
To simplify database architecture
Solution
Normalization is used to eliminate data anomalies and ensure data integrity by organizing data into related tables.
Correct Answer: B — To eliminate data anomalies
Q. What is the purpose of a data model in database design?
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A.
To define the physical storage of data
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B.
To represent data structures and relationships
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C.
To optimize query performance
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D.
To enforce data integrity constraints
Solution
A data model represents data structures and relationships, serving as a blueprint for database design.
Correct Answer: B — To represent data structures and relationships
Q. What is the purpose of a database schema?
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A.
To store data
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B.
To define the structure of the database
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C.
To manage user access
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D.
To optimize queries
Solution
A database schema defines the structure of the database, including tables, fields, relationships, and constraints.
Correct Answer: B — To define the structure of the database
Q. What is the purpose of concurrency control in a DBMS?
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A.
To manage data redundancy
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B.
To ensure data integrity during simultaneous transactions
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C.
To optimize query performance
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D.
To simplify database design
Solution
Concurrency control ensures data integrity when multiple transactions occur simultaneously in a database.
Correct Answer: B — To ensure data integrity during simultaneous transactions
Q. Which of the following is NOT a property of transactions in a DBMS?
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A.
Atomicity
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B.
Consistency
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C.
Isolation
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D.
Redundancy
Solution
Redundancy is not a property of transactions; the properties are known as ACID: Atomicity, Consistency, Isolation, and Durability.
Correct Answer: D — Redundancy
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