SMG IS 223 Lecture Notes - Lecture 13: Data Integrity, Data Modeling, Business Process Model And Notation
14 May 2018
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Department
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Professor
IS 13
ERD - Entity-Relationship Diagram - a data modeling tool for data designs
Business processes have data in motion = data is moved between actors
- Computer application programs move data around
- Data used to be moved around by humans
BPMN is used to show data and human action flow between actors in a business process
Businesses collect data and is stored at rest
- Data is organized and made easy to access
Entity Relationship Diagrams (ERDs) = Blueprint
A. ERD: diagrams that show relationship between data
B. Purpose: identify and understand data requirements from business perspective
Components of ERD
A. Entities - (entity class) something users want to track. person, place, or thing
a. Represents a type of object with some common characteristics
(attributes)
b. Can have an identifier - a unique characteristics/attribute Ex: order #
c. Entities are the “nouns” in out data model
d. In ERD, each entity is represented by a rectangle with a unique name
i. Entity names are singular
(“Student” not “students”)
B. Attributes - fields
a. Characteristics
of an entity or relationship
b. Data
that is important to collect
c. Represented with an ellipse
C. Relationships - (relationship class) relationship between entities
a. relationship s are the “verbs” or verb phrases
b. An instructor
(entity) teach (relationship) course
(entity) to a student
(entity)
c. Relationships are represented in a straight line connecting 2 entities
Good Database Design
A. Normalization - process of converting a poorly made table into two or more well structured tables
a. Goal of normalization is to have every table to have a single
topic
i. Ex: not employees and dept in on table. Split it into two individual tables
b. To normalize, can separate table into normal forms → each table should be separated
by its problems
c. “Those tables are not normalized
” = those tables have a format that could cause data
integrity problems
i. Data integrity problem - when there is inconsistent data
Document Summary
Erd - entity-relationship diagram - a data modeling tool for data designs. Business processes have data in motion = data is moved between actors. Data used to be moved around by humans. Bpmn is used to show data and human action flow between actors in a business process. Businesses collect data and is stored at rest. Data is organized and made easy to access: erd: diagrams that show relationship between data, purpose: identify and understand data requirements from business perspective. In erd, each entity is represented by a rectangle with a unique name d. i. Good database design: normalization - process of converting a poorly made table into two or more well structured tables i. Ex: not employees and dept in on table. Split it into two individual tables: goal of normalization is to have every table to have a single topic, to normalize, can separate table into normal forms each table should be separated by its problems.
