Lesson 3 Flashcards
usually the result of systematic analysis to define and describe what is important to processes in an area of a business.
ER Model
helps to explain the logical structure of database.
ER Diagram
three basic concepts of ERD:
*Entities
*Attributes
*Relationship
It is usually drawn in a graphical form as boxes
Entities
express the associations and dependencies between entities.
Relationship
(6) Uses of Entity Relationship Diagram
Education
Research
Database design
Database Troubleshooting
Business Information Systems
Business Process re-engineering
(sana wala sa exam)
An object or concept that is identified by the enterprise as having independent existence. It is
represented with rectangle.
Entity
Collection of entities of a particular type
Entity Instance
A property or the characteristics of an entity. It is presented as circle
Attribute
(7) Attributes types
- Simple
- Composite
- Single-valued
- Multi-valued
- Stored
6.Derived - Null values
Attributes that do not have any applicable values are said to have ____ ____.
Null Values
relate two or more entity types and defines a relationship set.
Relationship
Any given depiction of a relationship type is called ______
Relationship instance.
expresses whether the relationship is optional or mandatory.
Optionality
expresses the maximum number of relationships.
Cardinality
