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  • Data Modeling and Database DesignUAA ACCT 316Accounting Information SystemsDr. Fred Barbee5Chapter

  • Hmmm? What is data modeling?

  • What is Data Modeling?The Blind Men and the Elephant

  • What is Data Modeling?So what! You Say!

  • What is Data Modeling?Without a model of what we are building, we are like these blind men: we may be partly right, but we are probably mostly wrong.

  • What is Data Modeling?The elephant a third graders view.

  • What is Data Modeling?You cannot understand (and thus represent) something unless you comprehend it completely enterprise-wide.

  • What is Data Modeling?Platos Myth of the Cave

  • Hmmm? What is data modeling?

  • The Text Definition . . .Data modeling is the process of defining a database so that it faithfully represents all aspects of the organization, including its interactions with the external environment.

  • Other Definitions . . .Data modeling is the task of formalizing the data requirements of the business process as a conceptual model.Hall, James A. Accounting Information Systems Southwestern Publishing, 2001

  • Other Definitions . . .Data modeling is the process of defining what data you want to capture in your database and the relationships between data.Database Services University of Michigan http://www.umich.edu/~dbsvcs/services/modeling.html

  • Data Modeling and Database DesignDatabase Design Process5Chapter

  • Data Modeling Occurs HereFigure 5-1

  • Lets

    At each of these steps individually.The Database Design Process

  • PlanningRequirements AnalysisDesignCodingImplementationOperation andMaintenanceInitial planning to determine the need for and feasibility of developing a new system.

  • PlanningRequirements AnalysisDesignCodingImplementationOperation andMaintenanceIdentifying User Needs

  • PlanningRequirements AnalysisDesignCodingImplementationOperation andMaintenanceDeveloping the contextual-external- and internal-level schemas

  • PlanningRequirements AnalysisDesignCodingImplementationOperation andMaintenanceTranslating the internal-level schema into the actual database structures that will be implemented in the new system.

  • PlanningRequirements AnalysisDesignCodingImplementationOperation andMaintenanceTransferring all data from the existing system to the new database.

  • PlanningRequirements AnalysisDesignCodingImplementationOperation andMaintenanceUsing and maintaining the new system.

  • The Entity-Relationship (E-R) Diagram

  • The Entity-Relationship (E-R) Diagram

  • The REA Data Model

  • The REA Data ModelThe REA data model is a conceptual modeling tool specifically designed to provide structure for designing AIS data bases.

  • The REA Data ModelThe REA data model provides structure in two ways:By identifying what entities should be included in the AIS databaseBy prescribing how to structure relationships among the entities in the AIS database

  • Basic REA template

  • The REA Data ModelResourcesEventsAgents

  • The REA Data ModelResourcesEventsAgentsResources: Those things that have economic value to the firm.

  • The REA Data ModelResourcesEventsAgentsEvents: Various Business Activities

  • The REA Data ModelResourcesEventsAgentsAgents: People and Organizations that participate in events.

  • Developing an REA Diagram

  • Step 1: Identify the Economic Exchange EventsIdentify the pair of events that reflect the basic economic exchange (give-to-get duality relationship) in that cycle.1

  • Identify the PAIR of eventsOne GETOne GIVE

  • Step 2: Identify Resources and AgentsIdentify the Resources affected by each event and the agents who participate in those events.2

  • Identify . . .RESOURCES affected by each event.AGENTS who participate in the events.

  • Step 3: Include commitment EventsAnalyze each economic exchange event to determine whether it should be decomposed into a combination of one or more commitment events and an economic exchange event.3

  • Include commitment events.

  • Step 4: Determine Cardinalities of RelationshipsDetermine the cardinalities of each relationship.4

  • Determine cardinalities of relationships.

  • How many sales transactions can be linked to each individual customer?How many customers can be linked to each individual sales transaction?

  • Cardinalities(1,N)MinimumMaximum

  • The first number is the minimum cardinality. It indicates whether a row in this table must be linked to at least one row in the table on the opposite side of that relationship.

  • Minimum CardinalityThe minimum cardinality of a relationship indicates whether each row in that entity MUST be linked to a row in the entity on the other side of the relationship.Minimum cardinalities can be either 0 or 1.

  • Minimum CardinalitiesA minimum cardinality of zero means that a new row can be added to that table without being linked to any rows in the other table.A minimum cardinality of one means that each row in that table MUST be linked to at least one row in the other table

  • CardinalitiesSalesCustomer(0, N)The minimum cardinality of zero in the (0, N) cardinality pair to the left of the customer entity in the customer-sales relationship . . .. . . indicates that a new customer may be added to the database without being linked to any sales events.

  • CardinalitiesThe minimum cardinality of 1 in the (1,1) cardinality pair to the right of the sales entity in the customer-sales relationship . . .. . . indicates that a new sales transaction CAN ONLY be added if it is linked to a customer.SalesCustomer(0, N)(1,1)

  • The second number is the maximum cardinality. It indicates whether one row in that table can be linked to more than one row in the other table.

  • Maximum CardinalitiesThe maximum cardinality of a relationship indicates whether each row in that entity CAN be linked to more than one row in the entity on the other side of the relationship.Maximum cardinalities can be either 1 or N.

  • Maximum CardinalitiesA maximum cardinality of 1 means that each row in that table can be linked to at most only 1 row in the other table.A maximum cardinality of N means that each row in that table MAY be linked to more than one row in the other table.

  • CardinalitiesSalesCustomer(0, N)The maximum cardinality of N in the (0,N) cardinality pair to the left of the customer entity in the customer-sales relationship . . .. . . indicates that a given customer MAY be linked to many sales events.

  • CardinalitiesThe maximum cardinality of 1 in the (1,1) cardinality pair to the right of the sales entity in the customer-sales relationship . . .. . . indicates that a given sales transaction can only be linked to one customer.SalesCustomer(0, N)(1,1)

  • Determine CardinalitiesCardinalities are not arbitrarily chosen by the database designer.They reflect facts about the organization being modeled and its business practices obtained during the requirements analysis stage of the database design process.

  • Cardinalities: Types of RelationshipsThree basic types - depending on the maximum cardinality associated with each entity. A one-to-one relationship (1:1)A one-to-many relationship (1:N)A many-to-many relationship (M:N)

  • Types of RelationshipsPanel A: One-to-One (1:1) RelationshipSalesCash Receipts(0,1)(1,1)

  • Types of RelationshipsPanel B: One-to-Many (1:N) RelationshipSalesCash Receipts(0,N)(1,1)

  • Types of RelationshipsPanel C: One-to-Many (1:N) RelationshipSalesCash Receipts(0,1)(1,N)

  • Types of RelationshipsPanel D: Many-to-Many (M:N) RelationshipSalesCash Receipts(0,N)(1,N)

  • Build a Set of Tables to Implement an REA Model of an AIS in a Relational Database

  • Implementing an REA Diagram in a Relational DatabaseAn REA diagram can be used to design a well-structured relational database.A well-structured relational database is one that is not subject to update, insert, and delete anomaly problems.

  • Three Step ProcessCreate a table for each distinct entity and for each many-to many relationshipAssign attributes to appropriate tablesUse foreign keys to implement one-to-one and one-to-many relationships

  • Implementing an REA Diagram

  • Implementing an REA Diagram

  • Implementing an REA Diagram

    Chapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5: Data Modeling and Database DesignDr. Fred BarbeeChapter 5

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