DMC Conceptual and Logical Data Design 2

Question 1

What is a candidate key?

Accepted Answer

A minimal set of attributes that uniquely identifies each row in a relation

Answer

A candidate key is a minimal set of attributes (one or more columns) that can uniquely identify every row in a table, from which the primary key is chosen.

Question 2

In an ERD, what does the notation '1' on one side and 'M' on the other side of a relationship line indicate?

Accepted Answer

A one-to-many relationship between the two entities

Answer

The 1:M notation indicates a one-to-many relationship where one instance of the first entity can relate to many instances of the second.

Question 3

What technique is used in logical modeling to resolve a many-to-many relationship?

Accepted Answer

Creating an associative (bridge/intersection) entity

Answer

A many-to-many relationship is resolved by introducing an associative entity that holds the foreign keys of both related entities and may include relationship-specific attributes.

Question 4

Which design artifact maps source data fields to target data model attributes?

Accepted Answer

Data lineage map / data mapping document

Answer

A data mapping document (or lineage map) traces each source field to its target attribute, documenting transformations, business rules, and data origin.

Question 5

What is denormalization, and when is it appropriate?

Accepted Answer

Reversing normalization by intentionally adding redundancy to improve read performance

Answer

Denormalization intentionally introduces redundancy into a data model to improve query read performance, typically used in data warehouses or high-read OLAP systems.

DMC - Data Modeling Certification Practice Test

DMC - Data Modeling Certification Practice Test

DMC Conceptual and Logical Data Design 2