Conceptual and Logical Data Design Flashcards

In logical data modeling, what is the purpose of a business rule?

Answer: To capture constraints and policies that govern data and must be enforced by the model

Business rules define constraints, policies, and conditions that data must satisfy, and they guide the structure and constraints built into the logical data model.

What is a multi-valued attribute?

Answer: An attribute that can hold multiple independent values for a single entity instance

A multi-valued attribute is one that can hold more than one value simultaneously for the same entity, such as a person having multiple phone numbers.

Which normal form specifically addresses multi-valued dependencies?

Answer: 4NF

Fourth Normal Form (4NF) eliminates non-trivial multi-valued dependencies, ensuring a table doesn't independently store two or more multi-valued facts about an entity.

What is an abstract entity in a supertype/subtype model?

Answer: A supertype entity that cannot have direct instances — all instances must belong to a subtype

An abstract supertype has no instances of its own; every instance must be classified as one of its subtypes, such as EMPLOYEE being abstract with subtypes FULL_TIME and PART_TIME.

Which ERD notation style uses rectangles for entities, diamonds for relationships, and ovals for attributes?

Answer: Chen notation

Chen notation, developed by Peter Chen in 1976, uses rectangles for entities, diamonds for relationships, and ovals for attributes in its ERD representation.

In IDEF1X notation, what does a solid line between entities represent versus a dashed line?

Answer: Solid = identifying relationship; dashed = non-identifying relationship

In IDEF1X, a solid line represents an identifying relationship where the child's primary key includes the parent's key; a dashed line is a non-identifying relationship.