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Data Modeling

Business Analysis Techniques Series.Data models describe entities, classes or data objects relevant to a domain, their attributes and relationships among them.

Conceptual data model

Conceptual data models are independent of any solution and represents how business perceives its information. 

Logical data model

Logical data model normalizes data for data integrity, used to design a solution.

D:\LN\Mastering_BABoK_Diagrams_Paik\Slide29.PNG

Physical data model

Physical data models describe physical data organization in a database. Addresses concerns like performance, concurrency and security. Logical and physical data models include elements specific to solutions, developed by Implementation Subject Matter Experts. Check out Business Analyst Article for information about CBAP Certification, CCBA, ECBA

Entity or Class

Entities represent something physical (Warehouse), something organizational (Sales Area), something abstract (Product Line), or an event (Appointment). Entities are known as classes in class diagrams. Classes contain attributes and relationships with other classes, operations describing what can be done with class, such as generating an invoice or opening a bank account. Each instance of an entity or class has a unique ID.

https://lh3.googleusercontent.com/Pah903C1PYIpSEtXFaHDS2jn8QheYUQ3WGxCGaVDajGinhbxDNXtzM9m_O12oYRyaRyTykoXEmOKknN6l9IdeSCyPdYzhiS4Zsq20TjbXmtgV-VmsBy3_UYLw_FdLaSFvhjR9cM

Attribute: Attributes define particular piece of information associated with an entity, including size, allowable values and type of information it represents. Attributes should be described in a data dictionary. Business rules often specify allowable values. 

Cardinality

Cardinality defines minimum and maximum number of occurrences to which an entity is related another entity. Cardinality can be 0, 1 or many. 

One should read relationship between 2 entities in either direction, using this format: Each occurrence (of this entity) is related to (minimum, maximum) (of this other entity). 

In a class model, term association is used instead of relationship and multiplicity is used instead of cardinality.

Entity-Relationship Diagram (Crow’s Foot Notation)

D:\LN\Mastering_BABoK_Diagrams_Paik\Slide32.PNG

Metadata

Metadata describe what entities represent, when and why they were created or changed, how they should be used, usage frequency, when and by whom, restrictions on their creation or use, security, privacy and audit constraints on specific entities or groups of entities.

Strengths

  • Helps in consistent vocabulary.
  • Ensures logical design of persistent data correctly represents business needs.
  • Consistent approach to analyze and document data and its relationships.
  • Can be at different levels of detail.
  • Can expose missing requirements.

Limitations

  • Requires background in software.
  • Often beyond knowledge of individual stakeholders.

Worked out Example:

Let us learn data modelling by means of an example. Governance, Risk and Compliance (GRC) management system is developed for the IT and ITES domain. The primary objective of GRC management system is to help companies implement Governance, Quality, and Information Security Management Systems in an integrated manner. It has various features, one of which is to plan and track projects and programs using standards such as CMMI, ISO 9001, and ISO 27001 etc.

Through this example let us try to understand the entity relationship diagram and class diagram for the project schedule management module of Governance, Risk and Compliance management.

ER Diagram

Here, schedule is an entity with attributes such as ID, description, status and target date. The relationship between the entities schedule and schedule history is one to many. The relationship between user and schedule is many to many. A user can create several schedules. The relationship between two entities can be read from either direction.

Class diagram

C:\Users\Tahseen\Documents\Adaptive\Bhagya work\EQuiz-1\EQuiz\Clear images\863 - 28.jpg

In a class diagram, entities are referred to as classes. As seen in the diagram, the various classes are schedule, projects, schedule resources, project allocation and application users. A class contains a class name, attributes and operations respectively. Let us consider the schedule class and understand the 3 sections of a class. Schedule is the name of the class, WBS ID, Description, planned start date etc. are attributes and add and update are the operations you can carry out on the schedule class. This means a schedule can be added as well as updated.

A class has associations (same as relationship in entity model) with other classes. Here, the term multiplicity is used instead of cardinality. The association between a schedule resource and schedule is 0..* to 1 which means no resource or several resources can be assigned to a schedule.

Data Modeling

https://lh4.googleusercontent.com/iT9hiFQDhBvsoQh6fa4RioIMZkWGYwHV-bCyO6tdbodMvFDhJhlGqZnJO3hEoDb7ZrXdaBQnrJWFop08VEx87Pulbn3w1A_kMCRwbDKuIUgrq7hd0PycDODCcxTSWLoLf4xDXQg

Business Analysis Techniques Series.Data models describe entities, classes or data objects relevant to a domain, their attributes and relationships among them.

Conceptual data model

Conceptual data models are independent of any solution and represents how business perceives its information. 

Logical data model

Logical data model normalizes data for data integrity, used to design a solution.

D:\LN\Mastering_BABoK_Diagrams_Paik\Slide29.PNG

Physical data model

Physical data models describe physical data organization in a database. Addresses concerns like performance, concurrency and security. Logical and physical data models include elements specific to solutions, developed by Implementation Subject Matter Experts. Check out Business Analyst Article for information about CBAP Certification, CCBA, ECBA

Entity or Class

Entities represent something physical (Warehouse), something organizational (Sales Area), something abstract (Product Line), or an event (Appointment). Entities are known as classes in class diagrams. Classes contain attributes and relationships with other classes, operations describing what can be done with class, such as generating an invoice or opening a bank account. Each instance of an entity or class has a unique ID.

https://lh3.googleusercontent.com/Pah903C1PYIpSEtXFaHDS2jn8QheYUQ3WGxCGaVDajGinhbxDNXtzM9m_O12oYRyaRyTykoXEmOKknN6l9IdeSCyPdYzhiS4Zsq20TjbXmtgV-VmsBy3_UYLw_FdLaSFvhjR9cM

Attribute: Attributes define particular piece of information associated with an entity, including size, allowable values and type of information it represents. Attributes should be described in a data dictionary. Business rules often specify allowable values. 

Cardinality

Cardinality defines minimum and maximum number of occurrences to which an entity is related another entity. Cardinality can be 0, 1 or many. 

One should read relationship between 2 entities in either direction, using this format: Each occurrence (of this entity) is related to (minimum, maximum) (of this other entity). 

In a class model, term association is used instead of relationship and multiplicity is used instead of cardinality.

Entity-Relationship Diagram (Crow’s Foot Notation)

D:\LN\Mastering_BABoK_Diagrams_Paik\Slide32.PNG

Metadata

Metadata describe what entities represent, when and why they were created or changed, how they should be used, usage frequency, when and by whom, restrictions on their creation or use, security, privacy and audit constraints on specific entities or groups of entities.

Strengths

  • Helps in consistent vocabulary.
  • Ensures logical design of persistent data correctly represents business needs.
  • Consistent approach to analyze and document data and its relationships.
  • Can be at different levels of detail.
  • Can expose missing requirements.

Limitations

  • Requires background in software.
  • Often beyond knowledge of individual stakeholders.

Worked out Example:

Let us learn data modelling by means of an example. Governance, Risk and Compliance (GRC) management system is developed for the IT and ITES domain. The primary objective of GRC management system is to help companies implement Governance, Quality, and Information Security Management Systems in an integrated manner. It has various features, one of which is to plan and track projects and programs using standards such as CMMI, ISO 9001, and ISO 27001 etc.

Through this example let us try to understand the entity relationship diagram and class diagram for the project schedule management module of Governance, Risk and Compliance management.

ER Diagram

Here, schedule is an entity with attributes such as ID, description, status and target date. The relationship between the entities schedule and schedule history is one to many. The relationship between user and schedule is many to many. A user can create several schedules. The relationship between two entities can be read from either direction.

Class diagram

C:\Users\Tahseen\Documents\Adaptive\Bhagya work\EQuiz-1\EQuiz\Clear images\863 - 28.jpg

In a class diagram, entities are referred to as classes. As seen in the diagram, the various classes are schedule, projects, schedule resources, project allocation and application users. A class contains a class name, attributes and operations respectively. Let us consider the schedule class and understand the 3 sections of a class. Schedule is the name of the class, WBS ID, Description, planned start date etc. are attributes and add and update are the operations you can carry out on the schedule class. This means a schedule can be added as well as updated.

A class has associations (same as relationship in entity model) with other classes. Here, the term multiplicity is used instead of cardinality. The association between a schedule resource and schedule is 0..* to 1 which means no resource or several resources can be assigned to a schedule.

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