Info Systems

INFO243 Tutorial week 8

Q.1

REA focuses more on business events and is desgined to be looking at resources, events and agents. Traditional ERD is more looking at entities that are people rather than accounts, processes.

REA looking more along lines of control and responsibility and stock flow. Compared to an ERD, look more in-field, have to be recorded. REA is more about responsibility of each department.

Q.2

(a)

“modeling business events”- Take place in life of a business. i.e. Sales should be modeled, not specifically dr or cr, but taking a step back at each level as Xero does that for you.

(b)

Economic resource

Economic resource

Stock Flow

Stock Flow

Economic resource= inventory

Inventory is going out and is replaced by cash

Event

Event

(d)

Generalized model of a control relationship.

Responsi-bility

Responsi-bility

Control

Control

Economic resource

Economic resource

Eco Unit

Eco Unit

Eco agent

Eco agent

.

(e)

The economic Unit we deal with would be a sales representative. They have responsibility within eco unit, as they’re within the department, which has different levels of responbiilty and different department levels.

The Economic agent could be a customer/vendor.

Q.3

Applications approach: looking at each separate process, which has its own data base processing, not integrated- Legacy system. Problems: some data’s needed in some parts of system as well as others thus doubling up on data. Solved by using data base approach.

Data-base approach: Complete opposite- integrated, one part of the system can talk to another.

Q.4

Data independence in a database management system: data has to be stored separately to the application that uses it. Need to do that to achieve data base approach. i.e. stored in data warehouse and then quiered from the separate databases.

Q.5

(i)

Sales Order Product (many)

Sales Order Product (many)

(one) Product

(one) Product

Customer...