Data Models Flashcards
What is data modeling?
It is the creation of a specific data model for a determined problem domain
What is a data model?
It is a simple representation of complex real-world data structures
What is a model?
It is an abstraction of a more complex real-world object or event
Why is data modeling important?
Facilitates communication
Gives various views of the database
Organizes data for various users
Provides an abstraction for the creation of good a database
What is an entity?
It is a person, place, thing, or event about which data will be collected and stored
What is an attribute?
It is a characteristic of an entity
What is a relationship?
It is the association among entities
What is a constraint?
It is a restriction placed on data
What are business rules?
They are brief, precise, and unambiguous descriptions of a policy, procedure, or principle within a specific organization
What are the sources of business rules?
Company managers
Policy makers
Department managers
Written documentation
Direct interviews with end users
What are the reasons for identifying and documenting business rules?
Standardize company’s view of data
Facilitate communications tool between users and designers
Assist designers
What are relationships?
They are bidirectional
What are entity name requirements?
Be descriptive of the objects in the business environment
Use terminology that is familiar to the users
What are attribute names?
They are required to be descriptive of the data represented by the attribute
What does proper naming do?
Facilitates communication between parties
Promotes self-documentation
What are hierarchical models?
They are developed to manage a large amount of data for complex manufacturing projects
What are network models?
They are created to represent complex data relationships effectively
What is a table?
It is a logical construct perceived to be a two-dimensional structure composed of intersecting rows (entities) and columns (attributes) that represents an entity set in the relational model
What is a relational model?
It is a model based on a mathematical set theory and represents data as independent realtions
What is a relational database management system?
Performs basic functions provided by the hierarchical and network DBMS systems
Makes the relational data model easier to understand and implement
Hides the complexities of the relational model from the user
What is an SQL-based relational database application?
It is an end-user interface that allows end users to interact with the data
A collection of tables stored in the database
And an SQL engine that executes all queries
What is an Entity Relationship Diagram (ERD)?
It is a graphic representation to model database components
What is an entity instance or entity occurence?
It is the rows in the relational table
What is connectivity?
It is a term used to label relationship types
