Data Modelling..pptx
- 2. Introduction Process of creating a data model for an information system by applying formal data modeling techniques. Process used to define and analyze data requirements needed to support the business processes. Therefore, the process of data modeling involves professional data modelers working closely with business stakeholders, as well as potential users of the information system.
- 3. What is Data Model Data Model is a collection of conceptual tools for describing data, data relationships, data semantics and consistency constraint. A data model is a conceptual representation of data structures required for data base and is very powerful in expressing and communicating the business requirements A data model visually represents the nature of data, business rules governing the data, and how it will be organized in the database
- 4. A data model provides a way to describe the design of a database at the physical, logical and view levels. There are three different types of data models produced while progressing from requirements to the actual database to be used for the information system
- 5. Conceptual: describes WHAT the system contains Logical: describes HOW the system will be implemented, regardless of the DBMS Physical: describes HOW the system will be implemented using a specific DBMS Different Data Models
- 6. A data model consists of entities related to each other on a diagram:
- 7. Example: Given that Customer is an entity. Product is an entity. For a Customer we need to know their customer number attribute and name attribute. For a Product we need to know the product name attribute and price attribute. Sale is an entity that is used to record the interaction of Customer and Product.
- 8. Here is the diagram that encapsulates these rules:
- 9. Notes By convention, entities are named in the singular. The attributes of Customer are Customer No (which is the unique identifier or primary key of the Customer entity and is shown by the # symbol) and Customer Name. Sale has a composite primary key made up of the primary key of Customer, the primary key of Product and the date of the sale. Think of entities as tables, think of attributes as columns on the table and think of instances as rows on that table:
- 10. If we want to know the price of a Sale, we can find it by using the Product Code on the instance of Sale we are interested in and look up the corresponding Price on the Product entity with the matching Product Code.
- 11. Types of Data Models Entity-Relationship (E-R) Models UML (unified modeling language)
- 12. Entity-Relationship Model Entity Relationship Diagrams (ERD) as this is the most widely used ERDs have an advantage in that they are capable of being normalized Represent entities as rectangles List attributes within the rectangle UniversityStudent PK StudentID StudentName StudentDOB StudentAge Entity Attributes Primary key
- 13. Why and When The purpose of a data model is to describe the concepts relevant to a domain, the relationships between those concepts, and information associated with them
- 14. Significance of Model data Used to model data in a standard, consistent, predictable manner in order to manage it as a resource. To have a clear picture of the base data that your business needs To identify missing and redundant base data
- 15. Concluding To Establish a baseline for communication across functional boundaries within your organization Provides a basis for defining business rules Makes it cheaper, easier, and faster to upgrade your IT solutions