Chapter 2 Flashcards
What is Data modeling?
Data modeling is the first step in the database journey.
Works as a bridge between real-world objects and the computer database.
Data modeling refers to the process of creating a specific data model for a determined problem domain.
A data model is relatively simple representation, usually graphical, of more complex real-world structures.
What are the importances of data models?
communication tool
overall view of the database
organize data for various users
abstraction for the creation of good database
What is an Entity?
Unique and distinct object used to collect and store data
What is an Attribute?
Characteristic of an entity
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?
Help standardize company’s view of data
Communications tool between users and designers
Allow designers to:
o Understand the nature, role, scope of data, and business processes.
o Develop appropriate relationship participation rules and constraints
Create an accurate data model
How do Nouns translate into data models components?
Into entities
How do Verbs translate into data models components?
Into relationships among entities
What is hierarchal models mainly used for?
Developed to manage large amounts of data for complex manufacturing projects
What are the characteristics of a hierarchal model?
Represented by an upside-down tree which contains segments (equivalent of a file system’s record type)
Depicts a set of one-to-many (1:M) relationships
What are the Network Model created for?
Created to represent complex data relationships effectively
What are the characteristics of a network model?
Improved database performance and imposed a database standard
Allows a record to have more than one parent
Depicts both one-to-many (1:M) and many-to-many (M:N) relationships
What is a schema?
Conceptual organization of the entire database as viewed by the database administrator. Schema is the design/model we create.
What is a Subschema?
Portion of the database seen by the application programs that produce the desired information from the data within the database. The model without details. If we have to submit the work to the manager, sometimes they do not care about the records. They will only test it for a smaller part.
What is the relational model?
represents the database as a collection of relations. A relation is nothing but a table of values.
Based on a relation: Relation or table.
Tuple: Rows. Attribute: Columns
