Chapter 4-1

Chapter 4-2 Chapter 4: Data Modeling Introduction An Overview of Databases Steps in Creating a Database Using REA Creating Database Tables and Records

Chapter 4-3 Introduction Uses of a modern AIS  Systematically record data  Provide convenient and useful formats  Easy access to information

Chapter 4-4 What is a Database? Collection of related data Stored in computerized, linked files Manipulated by database management systems (DBMS)

Chapter 4-5 Importance of a Database? Valuable information Volume Complexity Privacy Irreplaceable data Need for accuracy Internet uses

Chapter 4-6 Data must be stored and organized efficiently Three important concepts:  Data hierarchy  Record structures  Record keys Storing Data in Databases

Chapter 4-7 Data Hierarchy Data organization in ascending order:  Bit (binary digit)  Byte (eight bits)  Data field  Record  File  Database

Chapter 4-8 Record Structures Data fields in each record Structure is usually fixed Example

Chapter 4-9 Record Keys Primary Record Key  Unique to each record Secondary Record Key  Non-unique identifiers  Used for searching files Foreign Keys

Chapter 4-10 Records Combined Into Report

Chapter 4-11 Additional Database Concerns Administration  Database Administrator Documentation  Includes a variety of descriptions  Structures, Contents, Security Features  Data Dictionary  Metadata

Chapter 4-12 Data Dictionary Example

Chapter 4-13 Additional Database Concerns Data Integrity  Data Integrity controls  Designed by database developers Processing Accuracy and Completeness  Transaction controls  Ensures transaction processing

Chapter 4-14 Additional Database Concerns Concurrency  Concurrency controls  Prevent multi-user access at same time Backup and Security  Ability to recreate data  Prevent unauthorized access  View controls

Chapter 4-15 Which of these is not part of the “data hierarchy” (within the context of databases)? A.Record B.Bit C.Character D.Data type Study Break #1

Chapter 4-16 Which of these is not part of the “data hierarchy” (within the context of databases)? A.Record B.Bit C.Character D.Data type Study Break #1 - Answer

Chapter 4-17 Within the context of databases, the term “concurrency” refers to the possibility that: A.A customer of one store might also be a customer of another store B.Two database users might want to access the same record at the same time C.A credit entry for a customer requires a debit entry for a matching account D.None of these Study Break #2

Chapter 4-18 Within the context of databases, the term “concurrency” refers to the possibility that: A.A customer of one store might also be a customer of another store B.Two database users might want to access the same record at the same time C.A credit entry for a customer requires a debit entry for a matching account D.None of these Study Break #2 - Answer

Chapter 4-19 REA Model Resources  Organization’s assets Events  Activities associated with a business processes Agents  People associated with business activities

Chapter 4-20 Identify Business and Economic Events Identify Entities Identify Relationships Among Entities Steps in Creating Databases with REA

Chapter 4-21 Create Entity-Relationship Diagrams Identify Attributes Entities Create Database Tables and Records to Validate the Database Steps in Creating Databases with REA

Chapter 4-22 Types of Events  Business  Economic Types of Database Entities  Events  Agents  Resources Identify Events and Entities

Chapter 4-23 Entity Examples

Chapter 4-24 Identify Relationships Among Entities Types of Relationships  Direct relationship  Indirect relationship Cardinalities  Nature of relationships among entities

Chapter 4-25 Cardinality Relationships Notations  One-to-one (1,1)  One-to-many (1,N)  None-to-one (0,1)  None-to-many (0,N)  Many-to-many (N,N) Purpose  Occurrence of one entity  Associated with occurrence of one event of another entity

Chapter 4-26 Purpose  Diagram entities  Relationships among entities Structure  Diamond symbols for relationships  Notations (1, 0, or N) for cardinalities Entity-Relationship Diagram

Chapter 4-27 E-R Diagram Symbols

Chapter 4-28 E-R Diagram With Cardinalities

Chapter 4-29 Organizing Database Records Database Structure  Method used to organize records  Develop efficient structure  Access data quickly and easily Three Types of Structures  Hierarchical  Network  Relational

Chapter 4-30 Hierarchical Structures Tree Structures  Successive levels of data  Inverted tree-like pattern Record Types  Parent records  Child records  Sibling records

Chapter 4-31 Network Structures Can link related records Capture many-to-many relationships Accomplished using pointer fields

Chapter 4-32 Relational Structures Provide greater flexibility Define relationships at different times  As database is created  At later points when relationships are identified

Chapter 4-33 Relational Structures

Chapter 4-34 Schematic of Database Tables

Chapter 4-35 In the REA model, the “A” stands for: A.Agents B.Additions C.Accounts D.Associations Study Break #3

Chapter 4-36 In the REA model, the “A” stands for: A.Agents B.Additions C.Accounts D.Associations Study Break #3 - Answer

Chapter 4-37 Which of these is not a cardinality between two database entities? A.One-to-one B.None-to-none C.One-to-many D.Many-to-many Study Break #4

Chapter 4-38 Which of these is not a cardinality between two database entities? A.One-to-one B.None-to-none C.One-to-many D.Many-to-many Study Break #4 - Answer

Chapter 4-39 A parent-child relationship between two records is characteristic of: A.Pyramid databases B.Network databases C.Hierarchical databases D.Family databases Study Break #5

Chapter 4-40 A parent-child relationship between two records is characteristic of: A.Pyramid databases B.Network databases C.Hierarchical databases D.Family databases Study Break #5 - Answer

Chapter 4-41 Creating Database Tables and Records An Introduction to Microsoft Access Creating Database Tables Creating Records Creating Database Relationships Guidelines for Creating Database Tables and Records

Chapter 4-42 Introduction to Microsoft Access A popular relational database Used by many businesses and individuals Used for small database applications

Chapter 4-43 Microsoft Access – Opening Screen

Chapter 4-44 Microsoft Access – Getting Started

Chapter 4-45 Creating Database Tables – Defining Record Format Field Name  Names assigned to the data fields Data Type  Specified for each data field Description  Optional field  Defines record structures

Chapter 4-46 Creating Database Tables – Opening Screen

Chapter 4-47 Creating Database Tables – Record Format

Chapter 4-48 Creating Records Utilize datasheet view to input data

Chapter 4-49 Creating Database Relationships Purpose  link tables together  enable users to create multi-table reports Steps in Creating Database Relationships  Launch the relationships window  Select tables  Link the tables

Chapter 4-50 Creating Database Relationships – Linking Tables

Chapter 4-51 Creating Database Relationships – Multi-Table Relationships

Chapter 4-52 Guidelines for Creating Database Tables and Records Design first  Create tables and records last Name tables systematically  Use conventional tbl prefixes Use mnemonic names for data fields Assign correct data types to data fields

Chapter 4-53 Guidelines for Creating Database Tables and Records Data fields that link tables must be the same data type Limit the size of text data fields to reasonable lengths Use input masks

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Chapter 4-55 Chapter 4