CHapter 3: conceptual data modeling

Question 1

What is conceptual data modeling?

Answer 1

• It is the development of an abstract model of reality
• Abstract model containing all relevant objects about which we want to store data

What information do the business activities require

Format of storing data is database

Question 2

Conceptual data modeling issues

Answer 2

• Contains ALL relevant objects about which we want to store data
• Format of storing data: text
• Not efficient in terms of retrieving info, from a technical perspective
• Not user friendly, not efficient in terms of memory usage, storage
• NOt structured
• Anybody can enter information in any format that they like

Question 3

What is database?

Answer 3

• Issues resolved by format of storing data (DATABASE)
• Infrastructure that is put in place
  o To store data in a predefined format
  o Allows easy retrieva;: every element can be located because its is names, identified, or described
  o Assigned an address
• Must represent real world things

Question 4

How do we develop a conceptual modeling cycle in the real world?

Answer 4

Observe the problem domain in the real world
The domain knowledge is the perception of the problem domain existinting in end users
it is gathered through observation and interviews. It is not reliable beecaus eit changes in time.
Afterwards, the domain knowledge should be explicitly specified-> externalizing the domain knowledge
Afterwards, i should be reviewed by the end-users
- interpret the model
Model knowledge is the interpretation of the model by end-users
Then the model knowledge and domain knlwedge are compared
This results in the valid model

This is important because it MINIMIZES risk. . Makes sure that the analysts and the owners both understand each other

Question 5

What are the tools available for conceptual modeling?

Answer 5

META model

• A meta model for conceptual modeling is a theory grounded in how reality can be described
• this theory is called ontology or meta-meta model
• facilitates the interpretation and validation of a model

Question 6

What are the 3 dimensioons or characteristics of a conceptual model?

Answer 6

• Specification
• Representation
• Agreement

Question 7

Whats the importance of conceptual data modeling?

Answer 7

It is an important determinant for

• system development costs: any errors and inconsistencies are more expensive and harder to fix during the design, implementation and maintenance stage, than if it discoveered during the analysis phase
• flexibility of the system: a well designed data model closely resembles reality, and thus can faciliitate changes in reality and the system in the model
• possibility to integrate with other systems: a well designed data model is easily interpretable thus facilitating the integration with other systems because they can be understood
• compliance with system requirements by the end users

Question 8

What is Semantic Expressiveness of a modeling method?

Answer 8

The power a modeling method offers to accurately describe reality, and all its elements with a limited set of constructs

Question 9

What do we want a conceptual data model to be able to express?

Answer 9

the relevant business domain objects -> business entities
the relationship between these objects -> busineess structure
the properties of the objects and its relationship -> business data
the rules that apply to these properties and relations -> business rules