Question

Data Models

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

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

3. What is a table, and what role does it play in the relational model?

Answer 1

• 1).
• Answer:-
• A business rule is a brief, precise, and unambiguous description of a policy, procedure, or principle within a specific organization.
• Properly written business rules are used to define entities, attributes, relationships, and constraints.
• Importance of Data Modeling:-
• data modeling is the process of creating a specific data model for a determined problem domain.
• It helps you determine how things piece together.
• The database designer uses data models to facilitate the interaction among designers, application programmers, and end users.

• 2).
• Answer:-
• A Relationship describes associations among data.
• Types of Relationships:-
• One to many (1:M).
• many to many (M:N).
• one to one (1:1).
• Examples for each Relationship types:-
• (1:M) – A person can own many cars; each car is owned by one person.
• (M:N) – A student can be in multiple classes; each class has multiple students.
• (1:1) – an employee manages one store; each store is managed by one employee.

• 3).
• Answer:-
• A table is a logical construct perceived to be a two-dimensional structure (matrix) composed of intersecting rows (entities) and columns (attributes) that represent an entity set in the relational model.

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