This chapter presented a high-level view of the database design process, and in this chapter we focus on the logical database design or data model mapping step of database design. We present the procedures to create a relational schema from an Entity-Relationship or an Enhanced ER schema. | CSC271 Database Systems Lecture # 26 Summary: Previous Lecture Enhanced Entity-Relationship (EER) model Specialization/Generalization Specialization/Generalization constraints Aggregation Composition Application of EER concepts to DreamHome Building Conceptual Data Model The tasks involved in building conceptual data model are: Identify entity types Identify relationship types Identify and associate attributes with entity or relationship types Determine attribute domains Determine candidate, primary, and alternate key attributes Consider use of enhanced modeling concepts (optional step) Check model for redundancy Validate conceptual model against user transactions Review conceptual data model with user Building Conceptual Data Model Identify relationship types Use Entity–Relationship (ER) diagrams Determine the multiplicity constraints of relationship types Used to check and maintain data quality Results in better representation of the data requirements of the enterprise Check for fan and chasm traps Document relationship types Staff User View Identify Relationship Types Building Conceptual Data Model Identify and associate attributes with entity or relationship types Simple/composite attributes Single/multi-valued attributes Two approaches, separate entity or as a multi-valued Derived attribute Document attributes Building Conceptual Data Model DreamHome Entities/Attributes Staff staffNo, name (composite: fName, lName), position, sex, DOB PropertyForRent propertyNo, address (composite: street, city, postcode), type, rooms, rent PrivateOwner ownerNo, name (composite: fName, lName), address, telNo BusinessOwner ownerNo, bName, bType, address, telNo, contactName Client clientNo, name (composite: fName, lName), telNo Preference prefType, maxRent Lease leaseNo, paymentMethod, deposit (derived as *2), depositPaid, rentStart, rentFinish, duration (derived as rentFinish – rentStart) Building Conceptual Data Model Determine attribute domains A . | CSC271 Database Systems Lecture # 26 Summary: Previous Lecture Enhanced Entity-Relationship (EER) model Specialization/Generalization Specialization/Generalization constraints Aggregation Composition Application of EER concepts to DreamHome Building Conceptual Data Model The tasks involved in building conceptual data model are: Identify entity types Identify relationship types Identify and associate attributes with entity or relationship types Determine attribute domains Determine candidate, primary, and alternate key attributes Consider use of enhanced modeling concepts (optional step) Check model for redundancy Validate conceptual model against user transactions Review conceptual data model with user Building Conceptual Data Model Identify relationship types Use Entity–Relationship (ER) diagrams Determine the multiplicity constraints of relationship types Used to check and maintain data quality Results in better representation of the data requirements of the enterprise Check for .
