2 Modeling & Designing the Database E-R ModelingDesign MethodologiesConceptualLogicalPhysical
3 EntityEntity Type -An object or concept that is identified by the enterprise as having an independent existence.Entity - An object or concept that is uniquely identifiable.Weak Entity Type - An entity type that is existence-dependent on some other entity type.
4 Attribute Attribute - A property of an entity or a relationship type. Attribute Domain - A set of values that may be assigned to a single-valued attribute.Composite Attribute – many componentsMulti-valued Attribute – set of valuesDerived Attribute - An attribute that represents a value that is derivable from the value of a related attribute or set of attributes, not necessarily in the same entity.
10 Database Design Methodology Three main phasesConceptual database design - The process of constructing a model of the information used in an enterprise, independent of all physical considerations.Logical database design - The process of constructing a model of the information used in an enterprise based on a specific data model, but independent of a particular DBMS and other physical considerations.Physical database design - The process of producing a description of the implementation of the database on secondary storage
11 Methodology Overview - Conceptual Database Design Step 1 Build local conceptual data model for each user viewStep 1.1 Identify entity typesStep 1.2 Identify relationship typesStep 1.3 Identify and associate attributes with entity or relationship typesStep 1.4 Determine attribute domainsStep 1.5 Determine candidate and primary key attributesStep 1.6 Specialize/generalize entity types (optional step)Step 1.7 Draw Entity–Relationship diagramStep 1.8 Review Local Conceptual Data Model with User
12 Methodology Overview - Logical Database Design for Relational Model Step 2 Build and Validate Local Logical Data ModelStep 2.1 Map Local Conceptual Data Model to Local Logical Data ModelStep 2.2 Derive Relations from Local Logical Data ModelStep 2.3 Validate Model using NormalizationStep 2.4 Validate Model against User TransactionsStep 2.5 Draw Entity-Relationship DiagramStep 2.6 Define Integrity ConstraintsStep 2.7 Review Local Logical Data Model with User
13 Methodology Overview - Logical Database Design for Relational Model Step 3 Build and Validate Global Logical Data ModelStep 3.1 Merge Local Logical Data Models into Global ModelStep 3.2 Validate Global Logical Data ModelStep 3.3 Check for Future GrowthStep 3.4 Draw Final Entity-Relationship Diagram
14 Methodology Overview - Physical Database Design for Relational Databases Step 4 Translate Global Logical Data Model for Target DBMSStep 4.1 Design Base Relations for Target DBMSStep 4.2 Design Integrity Rules for Target DBMSStep 5 Design Physical RepresentationStep 5.1 Analyze TransactionsStep 5.2 Choose File OrganizationStep 5.3 Choose Secondary IndexesStep 5.4 Consider the Introduction of Controlled RedundancyStep 5.5 Estimate Disk Space
15 Methodology Overview - Physical Database Design for Relational Databases Step 6 Design and Implement Security MechanismsStep 6.1 Design User ViewsStep 6.2 Design Access RulesStep 7 Monitor and Tune the Operational System