Database Chapter 2 Questions

What is a business rule, and what is its purpose in data modeling

A business rule is a brief, precise, and unambigous description of a policy, procedure, or principle within a specific organization's environment. Properly written business rules are used to define entities, attributes, relationships, and constraints. Because these components form the basis for a database design, the careful derivation and definition of business rules is crucial to good database design.

Describe the basic features of the relational data model and discuss their importance to the end user and the designer.*****

A relational database is a single data repository that provides both structural and data independence while maintaining conceptual simplicity. The relational model represents a breakthrough for users and designers because it lets them operate in a simpler conceptual environment. End users find it easier to visualize their data as a collection of data organized as a matrix. Designers find it easier to deal with conceptual data representation, freeing them from the complexities associated with physical data representation.

What is a relational diagram? Give an example.

A relational diagram is a visual representation of the relational database's entities, the attributes within those entities, and the relationships between those entities. Therefore, it is easy to see what the entities represent and to see what types of relationships (1:1, 1:M, M:N) exist among the entities and how those relationships are implemented. 2.

Explain how the entity relationship (ER) model helped produce a more structured relational database design environment.

An entity relationship model, also known as an ERM, helps identify the database's main entities and their relationships. Because the ERM components are graphically represented, their role is more easily understood. Using the ER diagram, it's easy to map the ERM to the relational database model's tables and attributes. This mapping process uses a series of well-defined steps to generate all the required database structures. Represents reality using well defined graphics and rules. Theoretical foundation Good for communication Translate to any type of DBMS

How do you translate business rules into data model components?

As a general rule, a noun in a business rule will translate into an entity in the model, and a verb (active or passive) associating nouns will translate into a relationship among the entities. For example, the business rule "a customer may generate many invoices" contains two nouns (customer and invoice) and a verb ("generate") that associates them.

What is physical independence?

Changes in physical model do not affect internal model

Discuss the importance of data modeling.

It is a way to represent reality. Is the blueprint for the database. The database designer uses data models to facilitate the interaction among designers, application programmers, and end users.

What is a relationship, and what three types of relationships exist?

Set of meaningful associations among entity types. Three types of relationships exist: one-to-one (1:1), one-to-many (1:M), and many-to-many (M:N or M:M.)

What is an ERDM, and what role does it play in the modern (production) database environment?

The Extended Relational Data Model (ERDM) is the relational data model's response to the Object Oriented Data Model (OODM.)

What is logical independence?

When you can change the internal model without affecting the conceptual model.