What is data model?

The first step in the process of database design.

What is a high-level conceptual data model?

Provides concepts for presenting data in ways that are close tot he way people perceive data.

What is an entity? An attribute? A relationship?

Entity – represents a real-world object such as an employee or a project.

Attribute – Represents properties such as an employee’s name, address and birth date.

Relationship – Represents an association among entities.

List and briefly describe the common record-based logical data models.

Relational data models – represents data as relations, or tables.

network data models – represents data as record types.

hierarchical data models – represents data as a hierarchical tree structure.

Describe the purpose of a conceptual design.

A step sometimes considered to be a high-level and abstract design phase.

How is a conceptual design different from a logical design?

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What is an external model?

The end user’s view of the data.

What is a conceptual model?

Is the first model created based on the needs of various departments.

What is an internal model?

Consider a database as a collection of fixed-size records

Are closer to the physical level or file structure

Are a representation of the database as seen by the DBMS

Require the designer to match the conceptual model’s characteristics and constraints to those of the selected implementation model

Involve mapping the entities in the conceptual model to the tables in the relational model

What is a physical model?

The way the data is stored on disk.

Which model does the database administrator work with?

external models

Which model does the end user work with?

external model

What is logical data independence?

The ability to change the logical schema, without changing the external schema or user view

What is physical data independence?

Deals with hiding the details of the storage structure from user applications