ORACLE microsystems Lecture 5 Entity-Relationship Model
Lecture 5 Entity-Relationship Model
1. Design Process 2.E-R Model 3.E-R diagram Outline 4.Advanced Topics 5. Reduction to relation schemas 6. Database design ZUML
Outline 1.Design Process 2.E-R Model 3.E-R Diagram 4.Advanced Topics 5.Reduction to Relation Schemas 6.Database Design 7.UML
Design Process
Design Process
Design Phases The initial phase of database design is to characterize fully the data needs of the prospective database users >Next, the designer chooses a data model and, by applying the concepts of the chosen data model, translates these requirements into a conceptual schema of the database >a fully developed conceptual schema also indicates the functional requirements of the enterprise. In a specification of functional requirements, users describe the kinds of operations or transactions that will be performed on the data
Design Phases ➢The initial phase of database design is to characterize fully the data needs of the prospective database users. ➢Next, the designer chooses a data model and, by applying the concepts of the chosen data model, translates these requirements into a conceptual schema of the database. ➢A fully developed conceptual schema also indicates the functional requirements of the enterprise. In a “specification of functional requirements”, users describe the kinds of operations (or transactions) that will be performed on the data
Design Phases(cont) The process of moving from an abstract data model to the implementation of the database proceeds in two final design phases. Logical Design- Deciding on the database schema. Database design requires that we find a good collection of relation schemas Business decision What attributes should we record in the database? Computer Science decision- What relation schemas should we have and how should the attributes be distributed among the various relation schemas? Physical Design- Deciding on the physical layout of the database
Design Phases(cont) ➢The process of moving from an abstract data model to the implementation of the database proceeds in two final design phases. • Logical Design – Deciding on the database schema. Database design requires that we find a “good” collection of relation schemas. • Business decision – What attributes should we record in the database? • Computer Science decision – What relation schemas should we have and how should the attributes be distributed among the various relation schemas? • Physical Design – Deciding on the physical layout of the database