Chapter 17: Database Design Using the REA Data Model Flashcards
5 basic steps of database design
- Systems Analysis
- Conceptual Design
- Physical Design
- Implementation and Conversion
- Operation and Maintenance
SCPIO
System Design
Step 1 of database design:
consists of intial planning to determine the need for and feasibility of developing a new system. It includes preliminary judgements about the proposal’s technological and economic feasibility. ID user information needs, defining the scope of the propose
Conceptual Design
Step 2 of database design:
includes developing the different schemas for the new system at the conceptual, external, and internal levels.
Physical Design
Step 3 of database design:
consists of translating the internal level schema into the actual database structures that will be implemented in the new system. This is also when new applications are developed
Implementation and Conversion
Step 4 of database design:
includes all the activities associated with transferring data from existing systems to the new database AIS, testing the new system, and training employees how to use it.
Using and Maintaining the new system
Step 5 of database design:
: it includes carefully monitoring system performance and user satisfaction to determine the need for making system enhancements and modifications.
Data Modeling
is the process of defining a database so that it faithfully represents all aspects of the organizations, including its interactions with the external environment. It occurs during both the systems analysis and conceptual design stages of database design.
two important tools that accountants use to perform data modeling
Entity-Relationship Diagramming and the REA Data Model
Entity-Relationship Diagram
a graphical technique for portraying a database schema (schema: the logical structure). It shows the various ENTITIES being modeled and the important relationships among them. (Only relationships between entities)
Entity
anything about which the organization wants to collect and store information.
Relationship
an association between two or more entities
REA data model
developed specifically for use in designing AIS. It focuses on the business semantics underlying an organization’s value-chain activities. It provides guidance for database design by identifying what entitles should be included in the AIS database. REA data models are usually depicted in the form of E-R diagrams.
3 basic types of entities
Resources the organization acquires and uses
Events in which the organization engages
Agents participating in these events
Resources
are those things that have economic value to the organization.
Events
are the various business activities about which management wants to collect information for planning or control purposes.
Agents
are the people and the organizations that participate in events and about whom information is desired for planning, control, and evaluation purposes.
3 General Rules
- Each event is linked to at least one resource that it affects
- Each event is linked to at least one other event
- Each event is linked to at least TWO participating agents
4 sequential activities in business
Take customer orders
Fill customer orders
Bill customers
Collect payment from customers.
3 questions to identifying resources and agents
- What economic resource is reduced by the “give” event?
- What economic resource is acquired by the “get” event?
- What economic resource is affected by a commitment event?
Cardinalities
describe the nature of the relationship between two entities by indicating how many instances of one entity can be linked to each specific instance of another entity.
Minimum Cardinality
either a zero or one, depending upon whether the relationship between the two entities is optional (the minimum cardinality is zero) or mandatory (the minimum cardinality is one).
Maximum Cardinality
can be either one or many (the crow feet symbol) depending upon whether each instance of entity A can be linked to at most one instance or potentially many instances of entity B.
3 basic types of relationships between entities:
1 to 1
1 to many
many to many
One to One relationship
exists when the maximum cardinality for each entity in that relationship is one.
One to many Relationship
exists when the maximum cardinality of one entity in the relationship is 1 and the maximum cardinality for the other entity in that relationship is many.
Many to Many relationship
exists when the maximum cardinality for both entities in the relationship is many
When does data modeling occur
both system analysis and conceptual design
