Accounting information systems 12th SIMKIN and norman chapter 03

Record Structures Data fields in each record of a database table Structure is usually fixed Example... Two database users might want to access the same record at the same time C... Tw

Chapter 3:

Data Modeling

Introduction

An Overview of Databases

Steps in Developing a Database Using

Resources, Events and Agents Model

Normalization

Uses of a modern AIS

What is a Database?

Collection of organized data

Used by many different computer

applications

Manipulated by database management

systems (DBMS)

Data must be stored and organized

Record Structures

Data fields in each record of a database table

Structure is usually fixed

Example

Database Keys

Primary Key

Foreign Keys

Records Combined Into

Report

Additional Database Issues

Administration

Documentation

Data Dictionary Example

Additional Database Issues

Data Integrity

Processing Accuracy and Completeness

Additional Database Issues

Concurrency

Backup and Security

The part of the data hierarchy that represents one instance of

The part of the data hierarchy that represents one instance of

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

Study Break #2

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

Identify Business and Economic Events

Identify Entities

Identify Relationships Among Entities

Steps in Developing Databases with REA

Create Entity-Relationship Diagrams

Identify Attributes of Entities

Convert E-R Diagrams into Database Tables

Steps in Developing Databases with REA

Entity Examples

 Occurrence of one entity

 Associated with occurrence of one event of another entity

Cardinality Relationships

Structure

Entity-Relationship Diagram

E-R Diagram Example

Relationship Tables

Provide greater flexibility

Need for Relationship Tables

Relationship Tables

Schematic of Database Tables

In the REA model, the “A” stands for:

In the REA model, the “A” stands for:

Which of these is not a cardinality between two database

Which of these is not a cardinality between two database

Normalization

 Methodology ensuring attributes are stored in most

appropriate tables

 Design promotes accuracy

 Avoids redundancy of data storage

Levels

 First normal form

 Second normal form

 Third normal form

Unnormalized Data

First Normal Form

In First Normal Form (1 NF) when:

Problems

First Normal Form Example

Second Normal Form

In Second Normal Form (2 NF) when:

Benefits

Second Normal Form

Example

Third Normal Form

In Third Normal Form (3 NF) when:

Ultimate Goal

Third Normal Form Example

A database is in third normal form (3NF) if it is second normal form and:

A All the data attributes in a record are well defined

B All the data attributes in a record depend on the record key

C The data contain to transitive dependencies

D The data can be stored in two or more separate tables

Study Break #5

A database is in third normal form (3NF) if it is second normal form and:

A All the data attributes in a record are well defined

B All the data attributes in a record depend on the record key

C The data contain to transitive dependencies

D The data can be stored in two or more separate tables

Study Break #5 - Answer

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Chapter 3