Question

A domain in a relational database refers to:

• A. The overall database structure
• B. A specific set of valid values for an attribute
• C. A table containing multiple records
• D. A relationship between two tables

Answer 1

The Correct Option is B

In the context of relational databases, a domain is a critical concept that refers to a specific set of valid values for an attribute. Each column in a table is associated with a particular domain, ensuring that each entry in the column falls within a predefined set of acceptable values. This is crucial for maintaining data integrity and consistency across the database. 

The options given highlight differing concepts within relational databases:

• The overall database structure: This refers to the schema of the database, including tables, relationships, and constraints.
• A specific set of valid values for an attribute: This describes a domain accurately, ensuring constraints are applied to data entries.
• A table containing multiple records: This is referred to as a table or relation, not a domain.
• A relationship between two tables: This is known as a foreign key relationship, connecting two tables through shared data.

Therefore, in a database schema, defining the domain for each attribute helps in maintaining robust data validation rules, aligning with the correct answer: A specific set of valid values for an attribute.

Answer 2

A domain in a relational database refers to a specific set of valid values for an attribute.

(1) The overall database structure: This describes the schema, not a single domain.

(2) A specific set of valid values for an attribute: A domain defines the set of possible values that an attribute can take. For instance, the domain of a "gender" attribute might be {"Male", "Female", "Other"}.

(3) A table containing multiple records: This describes a table or relation itself, not a domain.

(4) A relationship between two tables: This describes a relationship, such as a foreign key constraint, not a domain.

Therefore, a domain in a relational database refers to: (2) A specific set of valid values for an attribute.