SlideShare una empresa de Scribd logo
1 de 42
Descargar para leer sin conexión
Accounting Information Systems, 6th edition
                                  James A. Hall



COPYRIGHT © 2009 South-Western, a division of Cengage Learning. Cengage Learning and South-Western
                              are trademarks used herein under license
Objectives for Chapter 9
 Problems inherent in the flat file approach to data
 management that gave rise to the database concept
 Relationships among the defining elements of the
 database environment
 Anomalies caused by unnormalized databases and the
 need for data normalization
 Stages in database design: entity identification, data
 modeling, constructing the physical database, and
 preparing user views
 Features of distributed databases and issues to consider
 in deciding on a particular database configuration
Overview of the Flat‐File Versus 
Database Environments
 Computer processing involves two components: data
 and instructions (programs)
 Conceptually, there are two methods for designing the
 interface between program instructions and data:
    File-oriented processing: A specific data file was
    created for each application
    Data-oriented processing: Create a single data
    repository to support numerous applications.
 Disadvantages of file-oriented processing include
 redundant data and programs and varying formats for
 storing the redundant data.
Flat-File Environment
User 1                                 Data
Transactions
                  Program 1
                                       A,B,C

User 2
Transactions
                  Program 2            X,B,Y


User 3
Transactions
                  Program 3            L,B,M
Data Redundancy and Flat‐File 
Problems
Data Storage - creates excessive storage costs
of paper documents and/or magnetic form
Data Updating - any changes or additions must
be performed multiple times
Currency of Information - potential problem of
failing to update all affected files
Task-Data Dependency - user’s inability to
obtain additional information as his or her needs
change
Database Approach
User 1
                                   Database
Transactions
                 Program 1
                                     A,
User 2
                             D       B,
Transactions                 B       C,
                 Program 2   M       X,
                             S       Y,
User 3                               L,
Transactions                         M
                 Program 3
Advantages of the Database Approach
 Data sharing/centralize database resolves flat-file
  problems:
   No data redundancy: Data is stored only once,
   eliminating data redundancy and reducing storage
   costs.
   Single update: Because data is in only one place, it
   requires only a single update, reducing the time and
   cost of keeping the database current.
   Current values: A change to the database made by
   any user yields current data values for all other users.
   Task-data independence: As users’ information
   needs expand, the new needs can be more easily
   satisfied than under the flat-file approach.
Disadvantages of the Database Approach
   Can be costly to implement
     additional hardware, software, storage, and network
     resources are required
   Can only run in certain operating environments
     may make it unsuitable for some system
     configurations
   Because it is so different from
   the file-oriented approach, the database
   approach requires training users
     may be inertia or resistance
Internal Controls and DBMS
 The database management system (DBMS) stands
 between the user and the database per se.
 Thus, commercial DBMS’s (e.g., Access or Oracle)
 actually consist of a database plus…
   Plus software to manage the database, especially
   controlling access and other internal controls
   Plus software to generate reports, create data-entry
   forms, etc.
 The DBMS has special software to know which data
 elements each user is authorized to access and
 deny unauthorized requests of data.
System Requests   Elements of the Database Environment ‐‐Users
                                                Database
                           System Development   Administrator
                           Process


                                 Applications
                                   User              DBMS
                  Transactions
                                   Programs         Data
                                                    Definition     Host
           U                                        Language       Operating
           S      Transactions     User                            System
                                                    Data
           E                       Programs         Manipulation
           R                                        Language
           S      Transactions      User
                                                    Query
                                    Programs        Language       Physical
                                                                   Database



                            User Queries
Elements of the Database Environment ‐‐DBMS
DBMS Features
  Program Development - user created applications
  Backup and Recovery - copies database
  Database Usage Reporting - captures statistics on
  database usage (who, when, etc.)
  Database Access - authorizes access to sections of the
  database
  Also…
     User Programs - makes the presence of the DBMS
     transparent to the user
     Direct Query - allows authorized users to access data
     without programming
Data Definition Language (DDL)
 DDL is a programming language used to define
 the database per se.
   It identifies the names and the relationship of all data
   elements, records, and files that constitute the
   database.
 DDL defines the database on three viewing
 levels
   Internal view – physical arrangement of records (1
   view)
   Conceptual view (schema) – representation of
   database (1 view)
   User view (subschema) – the portion of the
   database each user views (many views)
Bab9
Data Manipulation Language (DML)
  DML is the proprietary programming language
  that a particular DBMS uses to retrieve,
  process, and store data to / from the database.
  Entire user programs may be written in the
  DML, or selected DML commands can be
  inserted into universal programs, such as
  COBOL and FORTRAN.
  Can be used to ‘patch’ third party applications
  to the DBMS
Query Language
  The query capability permits end users and
  professional programmers to access data in the
  database without the need for conventional
  programs.
    Can be an internal control issue since users may
    be making an ‘end run’ around the controls built
    into the conventional programs
  IBM’s structured query language (SQL) is a
  fourth-generation language that has emerged as
  the standard query language.
    Adopted by ANSI as the standard language for all
    relational databases
Functions of the DBA
Database Conceptual Models
 Refers to the particular method used to organize
 records in a database
    A.k.a. “logical data structures”
 Objective: develop the database efficiently so that
 data can be accessed quickly and easily
 There are three main models:
    hierarchical (tree structure)
    network
    relational
 Most existing databases are relational. Some legacy
 systems use hierarchical or network databases.
The Relational Model
  The relational model portrays data in the form
  of two dimensional ‘tables’.
  Its strength is the ease with which tables may
  be linked to one another.
    A major weakness of hierarchical and network
    databases
  Relational model is based on the relational
  algebra functions of restrict, project, and join.
Relational Algebra
RESTRICT – filtering out rows,           PROJECT – filtering out columns,
such as the dark blue                    such as the light blue




 JOIN – build a new table or data set from multiple existing tables


  X1     Y1          Y1     Z1                    X1     Y1     Z1


  X2     Y2          Y2     Z2                    X2     Y2     Z2


  X3     Y1          Y3     Z3                    X3     Y1     Z1
Associations and Cardinality
  Association – the labeled line connecting two
  entities or tables in a data model
    Describes the nature of the between them
    Represented with a verb, such as ships, requests, or
    receives
  Cardinality – the degree of association between
  two entities
    The number of possible occurrences in one table
    that are associated with a single occurrence in a
    related table
    Used to determine primary keys and foreign keys
“Crow’s Feet” Cardinalities
                       (1:0,1)



                        (1:1)



                       (1:0,M)


                       (1:M)



                       (M:M)
Properly Designed Relational Tables
   Each row in the table must be unique in at least
   one attribute, which is the primary key.
     Tables are linked by embedding the primary key
     into the related table as a foreign key.
   The attribute values in any column must all be of
   the same class or data type.
   Each column in a given table must be uniquely
   named.
   Tables must conform to the rules of
   normalization, i.e., free from structural
   dependencies or anomalies.
Three Types of Anomalies
Insertion Anomaly: A new item cannot be added to
the table until at least one entity uses a particular
attribute item.
Deletion Anomaly: If an attribute item used by only
one entity is deleted, all information about that attribute
item is lost.
Update Anomaly: A modification on an attribute must
be made in each of the rows in which the attribute
appears.
Anomalies can be corrected by creating additional
relational tables.
Advantages of Relational Tables
 Removes all three types of anomalies
 Various items of interest (customers,
 inventory, sales) are stored in separate
 tables.
 Space is used efficiently.
 Very flexible – users can form ad hoc
 relationships
The Normalization Process
 A process which systematically splits
 unnormalized complex tables into smaller
 tables that meet two conditions:
   all nonkey (secondary) attributes in the table are
   dependent on the primary key
   all nonkey attributes are independent of the other
   nonkey attributes
 When unnormalized tables are split and reduced to
 third normal form, they must then be linked
 together by foreign keys.
Steps in Normalization
Unnormalized table with
repeating groups            Remove
                           repeating
                            groups
First normal
form 1NF
                            Remove
                             partial
                          dependencies
Second normal
form 2NF
                             Remove
                            transitive
Third normal              dependencies
form 3NF

                              Remove
                             remaining
Higher normal                anomalies
forms
Accountants and Data Normalization
  Update anomalies can generate conflicting and
  obsolete database values.
  Insertion anomalies can result in unrecorded
  transactions and incomplete audit trails.
  Deletion anomalies can cause the loss of
  accounting records and the destruction of audit
  trails.
  Accountants should understand the data
  normalization process and be able to determine
  whether a database is properly normalized.
Six Phases in Designing Relational 
Databases
 1. Identify entities
    •   identify the primary entities of the
        organization
    •   construct a data model of their relationships
 2. Construct a data model showing entity
    associations
    •   determine the associations between entities
    •   model associations into an ER diagram
Six Phases in Designing Relational 
Databases
3. Add primary keys and attributes
   • assign primary keys to all entities in the
     model to uniquely identify records
   • every attribute should appear in one or
     more user views
4. Normalize and add foreign keys
   • remove repeating groups, partial and
     transitive dependencies
   • assign foreign keys to be able to link tables
Six Phases in Designing Relational 
Databases
 5. Construct the physical database
    • create physical tables
    • populate tables with data
 6. Prepare the user views
    • normalized tables should support all
      required views of system users
    • user views restrict users from have
      access to unauthorized data
Distributed Data Processing (DDP)
 Data processing is organized around several
 information processing units (IPUs) distributed
 throughout the organization.
    Each IPU is placed under the control of the end
    user.
 DDP does not always mean total decentralization.
    IPUs in a DDP system are still connected to one
    another and coordinated.
    Typically, DDP’s use a centralized database.
    Alternatively, the database can be distributed, similar
    to the distribution of the data processing capability.
Distributed Data
Processing


                   Central            Centralized
                   Site                Database




      Site A                 Site B      Site C
Centralized Databases in DDP 
Environment
 The data is retained in a central location.
 Remote IPUs send requests for data.
 Central site services the needs of the remote IPUs.
 The actual processing of the data is performed at the
 remote IPU.
Advantages of DDP
Cost reductions in hardware and data entry tasks
Improved cost control responsibility
Improved user satisfaction since control is closer
to the user level
Backup of data can be improved through the use of
multiple data storage sites
Disadvantages of DDP
 Loss of control
 Mismanagement of resources
 Hardware and software incompatibility
 Redundant tasks and data
 Consolidating incompatible tasks
 Difficulty attracting qualified personnel
 Lack of standards
Data Currency
Occurs in DDP with a centralized
database
During transaction processing, data will
temporarily be inconsistent as records are
read and updated.
Database lockout procedures are
necessary to keep IPUs from reading
inconsistent data and from writing over a
transaction being written by another IPU.
Distributed Databases: Partitioning
  Splits the central database into segments
  that are distributed to their primary users
  Advantages:
    users’ control is increased by having data
    stored at local sites
    transaction processing response time is
    improved
    volume of transmitted data between IPUs is
    reduced
    reduces the potential data loss from a disaster
The Deadlock Phenomenon
   Especially a problem with
   partitioned databases
   Occurs when multiple sites lock each other
   out of data that they are currently using
     One site needs data locked by another site.
   Special software is needed to analyze and
   resolve conflicts.
     Transactions may be terminated and restarted.
The Deadlock Phenomenon
Locked A, waiting for C          Locked E, waiting for A

A,B
                                                     E, F




             C,D

                 Locked C, waiting for E
Distributed Databases: Replication
    The duplication of the entire
    database for multiple IPUs
    Effective for situations with a high
    degree of data sharing, but no
    primary user
      Supports read-only queries
    Data traffic between sites is
    reduced considerably.
Concurrency Problems and Control 
Issues
Database concurrency is the presence of
complete and accurate data at all IPU sites.
With replicated databases, maintaining current
data at all locations is difficult.
Time stamping is used to serialize
transactions.
  Prevents and resolves conflicts created by
  updating data at various IPUs
Distributed Databases and the 
Accountant
 The following database options impact the
 organization’s ability to maintain database integrity,
 to preserve audit trails, and to have accurate
 accounting records.
   Centralized or distributed data?
   If distributed, replicated or partitioned?
   If replicated, totally or partially replication?
   If partitioned, what allocation of the data segments
   among the sites?

Más contenido relacionado

La actualidad más candente

Basic Concept Of Database Management System (DBMS) [Presentation Slide]
Basic Concept Of Database Management System (DBMS) [Presentation Slide]Basic Concept Of Database Management System (DBMS) [Presentation Slide]
Basic Concept Of Database Management System (DBMS) [Presentation Slide]Atik Israk
 
Kskv kutch university DBMS unit 1 basic concepts, data,information,database,...
Kskv kutch university DBMS unit 1  basic concepts, data,information,database,...Kskv kutch university DBMS unit 1  basic concepts, data,information,database,...
Kskv kutch university DBMS unit 1 basic concepts, data,information,database,...Dipen Parmar
 
Fundamentals of Database system
Fundamentals of Database systemFundamentals of Database system
Fundamentals of Database systemphilipsinter
 
Bsc cs ii-dbms- u-ii-database system concepts and architecture
Bsc cs ii-dbms- u-ii-database system concepts and architectureBsc cs ii-dbms- u-ii-database system concepts and architecture
Bsc cs ii-dbms- u-ii-database system concepts and architectureRai University
 
Databaseconcepts
DatabaseconceptsDatabaseconcepts
Databaseconceptskissumadanu
 
Ansi spark
Ansi sparkAnsi spark
Ansi sparkjani
 
Database system concepts and architecture
Database system concepts and architectureDatabase system concepts and architecture
Database system concepts and architectureJafar Nesargi
 
Dbms Concepts
Dbms ConceptsDbms Concepts
Dbms Conceptsadukkas
 
Basic Concept of Database
Basic Concept of DatabaseBasic Concept of Database
Basic Concept of DatabaseMarlon Jamera
 
Database Management System And Design Questions
Database Management System And Design QuestionsDatabase Management System And Design Questions
Database Management System And Design QuestionsSamir Sabry
 
Data base management system
Data base management systemData base management system
Data base management systemashirafzal1
 
Database management system chapter1
Database management system chapter1Database management system chapter1
Database management system chapter1Pranab Dasgupta
 
Chapter 2 database architecture
Chapter 2 database architectureChapter 2 database architecture
Chapter 2 database architectureUra Euro
 

La actualidad más candente (20)

Dbms
DbmsDbms
Dbms
 
Basic Concept Of Database Management System (DBMS) [Presentation Slide]
Basic Concept Of Database Management System (DBMS) [Presentation Slide]Basic Concept Of Database Management System (DBMS) [Presentation Slide]
Basic Concept Of Database Management System (DBMS) [Presentation Slide]
 
Kskv kutch university DBMS unit 1 basic concepts, data,information,database,...
Kskv kutch university DBMS unit 1  basic concepts, data,information,database,...Kskv kutch university DBMS unit 1  basic concepts, data,information,database,...
Kskv kutch university DBMS unit 1 basic concepts, data,information,database,...
 
Fundamentals of Database system
Fundamentals of Database systemFundamentals of Database system
Fundamentals of Database system
 
Bsc cs ii-dbms- u-ii-database system concepts and architecture
Bsc cs ii-dbms- u-ii-database system concepts and architectureBsc cs ii-dbms- u-ii-database system concepts and architecture
Bsc cs ii-dbms- u-ii-database system concepts and architecture
 
Databaseconcepts
DatabaseconceptsDatabaseconcepts
Databaseconcepts
 
Ansi spark
Ansi sparkAnsi spark
Ansi spark
 
Database system concepts and architecture
Database system concepts and architectureDatabase system concepts and architecture
Database system concepts and architecture
 
Database Chapter 1
Database Chapter 1Database Chapter 1
Database Chapter 1
 
Dbms Concepts
Dbms ConceptsDbms Concepts
Dbms Concepts
 
RDBMS.ppt
RDBMS.pptRDBMS.ppt
RDBMS.ppt
 
Dbms
DbmsDbms
Dbms
 
Dbms
DbmsDbms
Dbms
 
Basic Concept of Database
Basic Concept of DatabaseBasic Concept of Database
Basic Concept of Database
 
Database Systems Concepts, 5th Ed
Database Systems Concepts, 5th EdDatabase Systems Concepts, 5th Ed
Database Systems Concepts, 5th Ed
 
Database Management System And Design Questions
Database Management System And Design QuestionsDatabase Management System And Design Questions
Database Management System And Design Questions
 
Data base management system
Data base management systemData base management system
Data base management system
 
Database management system chapter1
Database management system chapter1Database management system chapter1
Database management system chapter1
 
Chapter 2 database architecture
Chapter 2 database architectureChapter 2 database architecture
Chapter 2 database architecture
 
Database language
Database languageDatabase language
Database language
 

Destacado (17)

Plugin ch12edited-ok
Plugin ch12edited-okPlugin ch12edited-ok
Plugin ch12edited-ok
 
Plugin ch11edited-ok
Plugin ch11edited-okPlugin ch11edited-ok
Plugin ch11edited-ok
 
Bab4
Bab4Bab4
Bab4
 
Plugin ch06
Plugin ch06Plugin ch06
Plugin ch06
 
Plugin ch05
Plugin ch05Plugin ch05
Plugin ch05
 
Plugin ch07
Plugin ch07Plugin ch07
Plugin ch07
 
Bab1
Bab1Bab1
Bab1
 
Bab2
Bab2Bab2
Bab2
 
Pertemuan7
Pertemuan7Pertemuan7
Pertemuan7
 
Pertemuan4
Pertemuan4Pertemuan4
Pertemuan4
 
Penjelasan strukturdata
Penjelasan strukturdataPenjelasan strukturdata
Penjelasan strukturdata
 
Pertemuan5
Pertemuan5Pertemuan5
Pertemuan5
 
Plugin rea-romney
Plugin rea-romneyPlugin rea-romney
Plugin rea-romney
 
Plugin sesi-6-jah-bab-3
Plugin sesi-6-jah-bab-3Plugin sesi-6-jah-bab-3
Plugin sesi-6-jah-bab-3
 
Rsi 14
Rsi 14Rsi 14
Rsi 14
 
Bab9
Bab9Bab9
Bab9
 
Audit presentation
Audit presentationAudit presentation
Audit presentation
 

Similar a Bab9

Introduction to Database
Introduction to DatabaseIntroduction to Database
Introduction to DatabaseSiti Ismail
 
database introductoin optimization1-app6891.pdf
database introductoin optimization1-app6891.pdfdatabase introductoin optimization1-app6891.pdf
database introductoin optimization1-app6891.pdfparveen204931475
 
21UCAC 41 Database Management System.ppt
21UCAC 41 Database Management System.ppt21UCAC 41 Database Management System.ppt
21UCAC 41 Database Management System.pptssuser7f90ae
 
Database systems - Chapter 2 (Remaining)
Database systems - Chapter 2 (Remaining)Database systems - Chapter 2 (Remaining)
Database systems - Chapter 2 (Remaining)shahab3
 
Introduction to DBMS.pptx
Introduction to DBMS.pptxIntroduction to DBMS.pptx
Introduction to DBMS.pptxSreenivas R
 
Ch1
Ch1Ch1
Ch1CAG
 
1. Introduction to DBMS
1. Introduction to DBMS1. Introduction to DBMS
1. Introduction to DBMSkoolkampus
 
Database management system
Database management systemDatabase management system
Database management systemRizwanHafeez
 
Introduction & history of dbms
Introduction & history of dbmsIntroduction & history of dbms
Introduction & history of dbmssethu pm
 

Similar a Bab9 (20)

James hall ch 9
James hall ch 9James hall ch 9
James hall ch 9
 
Introduction to Database
Introduction to DatabaseIntroduction to Database
Introduction to Database
 
database introductoin optimization1-app6891.pdf
database introductoin optimization1-app6891.pdfdatabase introductoin optimization1-app6891.pdf
database introductoin optimization1-app6891.pdf
 
21UCAC 41 Database Management System.ppt
21UCAC 41 Database Management System.ppt21UCAC 41 Database Management System.ppt
21UCAC 41 Database Management System.ppt
 
Database systems - Chapter 2 (Remaining)
Database systems - Chapter 2 (Remaining)Database systems - Chapter 2 (Remaining)
Database systems - Chapter 2 (Remaining)
 
Introduction to DBMS.pptx
Introduction to DBMS.pptxIntroduction to DBMS.pptx
Introduction to DBMS.pptx
 
Ch1
Ch1Ch1
Ch1
 
Ch1
Ch1Ch1
Ch1
 
Ch1 2
Ch1 2Ch1 2
Ch1 2
 
1. Introduction to DBMS
1. Introduction to DBMS1. Introduction to DBMS
1. Introduction to DBMS
 
Dbms 1
Dbms 1Dbms 1
Dbms 1
 
DataMgt - UNIT-I .PPT
DataMgt - UNIT-I .PPTDataMgt - UNIT-I .PPT
DataMgt - UNIT-I .PPT
 
Database management system
Database management systemDatabase management system
Database management system
 
Introduction & history of dbms
Introduction & history of dbmsIntroduction & history of dbms
Introduction & history of dbms
 
Database management systems
Database management systemsDatabase management systems
Database management systems
 
DBMS
DBMSDBMS
DBMS
 
database
databasedatabase
database
 
En ch01
En ch01En ch01
En ch01
 
Dbms unit01
Dbms unit01Dbms unit01
Dbms unit01
 
Unit 01 dbms
Unit 01 dbmsUnit 01 dbms
Unit 01 dbms
 

Más de donasiilmu

Más de donasiilmu (20)

Isi
IsiIsi
Isi
 
Dftr isi
Dftr isiDftr isi
Dftr isi
 
Pengantar
PengantarPengantar
Pengantar
 
9 materisim komputer
9 materisim komputer9 materisim komputer
9 materisim komputer
 
Interaksi manusia dan komputer
Interaksi manusia dan komputerInteraksi manusia dan komputer
Interaksi manusia dan komputer
 
Makalah jaringan-komputer2
Makalah jaringan-komputer2Makalah jaringan-komputer2
Makalah jaringan-komputer2
 
Makalah jaringan-komputer2
Makalah jaringan-komputer2Makalah jaringan-komputer2
Makalah jaringan-komputer2
 
Apsi
ApsiApsi
Apsi
 
Data flow diagram
Data flow diagramData flow diagram
Data flow diagram
 
Erd
ErdErd
Erd
 
Norma lisasi
Norma lisasiNorma lisasi
Norma lisasi
 
Pertemuan6
Pertemuan6Pertemuan6
Pertemuan6
 
Pertemuan9
Pertemuan9Pertemuan9
Pertemuan9
 
Pertemuan10
Pertemuan10Pertemuan10
Pertemuan10
 
Pertemuan10
Pertemuan10Pertemuan10
Pertemuan10
 
Pertemuan11
Pertemuan11Pertemuan11
Pertemuan11
 
Pertemuan12
Pertemuan12Pertemuan12
Pertemuan12
 
Pertemuan13
Pertemuan13Pertemuan13
Pertemuan13
 
Pertemuan14
Pertemuan14Pertemuan14
Pertemuan14
 
Uas
UasUas
Uas
 

Último

Drug Information Services- DIC and Sources.
Drug Information Services- DIC and Sources.Drug Information Services- DIC and Sources.
Drug Information Services- DIC and Sources.raviapr7
 
How to Make a Field read-only in Odoo 17
How to Make a Field read-only in Odoo 17How to Make a Field read-only in Odoo 17
How to Make a Field read-only in Odoo 17Celine George
 
Prescribed medication order and communication skills.pptx
Prescribed medication order and communication skills.pptxPrescribed medication order and communication skills.pptx
Prescribed medication order and communication skills.pptxraviapr7
 
5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...CaraSkikne1
 
The Singapore Teaching Practice document
The Singapore Teaching Practice documentThe Singapore Teaching Practice document
The Singapore Teaching Practice documentXsasf Sfdfasd
 
UKCGE Parental Leave Discussion March 2024
UKCGE Parental Leave Discussion March 2024UKCGE Parental Leave Discussion March 2024
UKCGE Parental Leave Discussion March 2024UKCGE
 
Human-AI Co-Creation of Worked Examples for Programming Classes
Human-AI Co-Creation of Worked Examples for Programming ClassesHuman-AI Co-Creation of Worked Examples for Programming Classes
Human-AI Co-Creation of Worked Examples for Programming ClassesMohammad Hassany
 
Philosophy of Education and Educational Philosophy
Philosophy of Education  and Educational PhilosophyPhilosophy of Education  and Educational Philosophy
Philosophy of Education and Educational PhilosophyShuvankar Madhu
 
How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17Celine George
 
Presentation on the Basics of Writing. Writing a Paragraph
Presentation on the Basics of Writing. Writing a ParagraphPresentation on the Basics of Writing. Writing a Paragraph
Presentation on the Basics of Writing. Writing a ParagraphNetziValdelomar1
 
Education and training program in the hospital APR.pptx
Education and training program in the hospital APR.pptxEducation and training program in the hospital APR.pptx
Education and training program in the hospital APR.pptxraviapr7
 
Patterns of Written Texts Across Disciplines.pptx
Patterns of Written Texts Across Disciplines.pptxPatterns of Written Texts Across Disciplines.pptx
Patterns of Written Texts Across Disciplines.pptxMYDA ANGELICA SUAN
 
DUST OF SNOW_BY ROBERT FROST_EDITED BY_ TANMOY MISHRA
DUST OF SNOW_BY ROBERT FROST_EDITED BY_ TANMOY MISHRADUST OF SNOW_BY ROBERT FROST_EDITED BY_ TANMOY MISHRA
DUST OF SNOW_BY ROBERT FROST_EDITED BY_ TANMOY MISHRATanmoy Mishra
 
Patient Counselling. Definition of patient counseling; steps involved in pati...
Patient Counselling. Definition of patient counseling; steps involved in pati...Patient Counselling. Definition of patient counseling; steps involved in pati...
Patient Counselling. Definition of patient counseling; steps involved in pati...raviapr7
 
In - Vivo and In - Vitro Correlation.pptx
In - Vivo and In - Vitro Correlation.pptxIn - Vivo and In - Vitro Correlation.pptx
In - Vivo and In - Vitro Correlation.pptxAditiChauhan701637
 
General views of Histopathology and step
General views of Histopathology and stepGeneral views of Histopathology and step
General views of Histopathology and stepobaje godwin sunday
 
The Stolen Bacillus by Herbert George Wells
The Stolen Bacillus by Herbert George WellsThe Stolen Bacillus by Herbert George Wells
The Stolen Bacillus by Herbert George WellsEugene Lysak
 
How to Add a many2many Relational Field in Odoo 17
How to Add a many2many Relational Field in Odoo 17How to Add a many2many Relational Field in Odoo 17
How to Add a many2many Relational Field in Odoo 17Celine George
 
AUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptxAUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptxiammrhaywood
 

Último (20)

Drug Information Services- DIC and Sources.
Drug Information Services- DIC and Sources.Drug Information Services- DIC and Sources.
Drug Information Services- DIC and Sources.
 
Finals of Kant get Marx 2.0 : a general politics quiz
Finals of Kant get Marx 2.0 : a general politics quizFinals of Kant get Marx 2.0 : a general politics quiz
Finals of Kant get Marx 2.0 : a general politics quiz
 
How to Make a Field read-only in Odoo 17
How to Make a Field read-only in Odoo 17How to Make a Field read-only in Odoo 17
How to Make a Field read-only in Odoo 17
 
Prescribed medication order and communication skills.pptx
Prescribed medication order and communication skills.pptxPrescribed medication order and communication skills.pptx
Prescribed medication order and communication skills.pptx
 
5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...
 
The Singapore Teaching Practice document
The Singapore Teaching Practice documentThe Singapore Teaching Practice document
The Singapore Teaching Practice document
 
UKCGE Parental Leave Discussion March 2024
UKCGE Parental Leave Discussion March 2024UKCGE Parental Leave Discussion March 2024
UKCGE Parental Leave Discussion March 2024
 
Human-AI Co-Creation of Worked Examples for Programming Classes
Human-AI Co-Creation of Worked Examples for Programming ClassesHuman-AI Co-Creation of Worked Examples for Programming Classes
Human-AI Co-Creation of Worked Examples for Programming Classes
 
Philosophy of Education and Educational Philosophy
Philosophy of Education  and Educational PhilosophyPhilosophy of Education  and Educational Philosophy
Philosophy of Education and Educational Philosophy
 
How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17
 
Presentation on the Basics of Writing. Writing a Paragraph
Presentation on the Basics of Writing. Writing a ParagraphPresentation on the Basics of Writing. Writing a Paragraph
Presentation on the Basics of Writing. Writing a Paragraph
 
Education and training program in the hospital APR.pptx
Education and training program in the hospital APR.pptxEducation and training program in the hospital APR.pptx
Education and training program in the hospital APR.pptx
 
Patterns of Written Texts Across Disciplines.pptx
Patterns of Written Texts Across Disciplines.pptxPatterns of Written Texts Across Disciplines.pptx
Patterns of Written Texts Across Disciplines.pptx
 
DUST OF SNOW_BY ROBERT FROST_EDITED BY_ TANMOY MISHRA
DUST OF SNOW_BY ROBERT FROST_EDITED BY_ TANMOY MISHRADUST OF SNOW_BY ROBERT FROST_EDITED BY_ TANMOY MISHRA
DUST OF SNOW_BY ROBERT FROST_EDITED BY_ TANMOY MISHRA
 
Patient Counselling. Definition of patient counseling; steps involved in pati...
Patient Counselling. Definition of patient counseling; steps involved in pati...Patient Counselling. Definition of patient counseling; steps involved in pati...
Patient Counselling. Definition of patient counseling; steps involved in pati...
 
In - Vivo and In - Vitro Correlation.pptx
In - Vivo and In - Vitro Correlation.pptxIn - Vivo and In - Vitro Correlation.pptx
In - Vivo and In - Vitro Correlation.pptx
 
General views of Histopathology and step
General views of Histopathology and stepGeneral views of Histopathology and step
General views of Histopathology and step
 
The Stolen Bacillus by Herbert George Wells
The Stolen Bacillus by Herbert George WellsThe Stolen Bacillus by Herbert George Wells
The Stolen Bacillus by Herbert George Wells
 
How to Add a many2many Relational Field in Odoo 17
How to Add a many2many Relational Field in Odoo 17How to Add a many2many Relational Field in Odoo 17
How to Add a many2many Relational Field in Odoo 17
 
AUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptxAUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptx
 

Bab9

  • 1. Accounting Information Systems, 6th edition James A. Hall COPYRIGHT © 2009 South-Western, a division of Cengage Learning. Cengage Learning and South-Western are trademarks used herein under license
  • 2. Objectives for Chapter 9 Problems inherent in the flat file approach to data management that gave rise to the database concept Relationships among the defining elements of the database environment Anomalies caused by unnormalized databases and the need for data normalization Stages in database design: entity identification, data modeling, constructing the physical database, and preparing user views Features of distributed databases and issues to consider in deciding on a particular database configuration
  • 3. Overview of the Flat‐File Versus  Database Environments Computer processing involves two components: data and instructions (programs) Conceptually, there are two methods for designing the interface between program instructions and data: File-oriented processing: A specific data file was created for each application Data-oriented processing: Create a single data repository to support numerous applications. Disadvantages of file-oriented processing include redundant data and programs and varying formats for storing the redundant data.
  • 4. Flat-File Environment User 1 Data Transactions Program 1 A,B,C User 2 Transactions Program 2 X,B,Y User 3 Transactions Program 3 L,B,M
  • 5. Data Redundancy and Flat‐File  Problems Data Storage - creates excessive storage costs of paper documents and/or magnetic form Data Updating - any changes or additions must be performed multiple times Currency of Information - potential problem of failing to update all affected files Task-Data Dependency - user’s inability to obtain additional information as his or her needs change
  • 6. Database Approach User 1 Database Transactions Program 1 A, User 2 D B, Transactions B C, Program 2 M X, S Y, User 3 L, Transactions M Program 3
  • 7. Advantages of the Database Approach Data sharing/centralize database resolves flat-file problems: No data redundancy: Data is stored only once, eliminating data redundancy and reducing storage costs. Single update: Because data is in only one place, it requires only a single update, reducing the time and cost of keeping the database current. Current values: A change to the database made by any user yields current data values for all other users. Task-data independence: As users’ information needs expand, the new needs can be more easily satisfied than under the flat-file approach.
  • 8. Disadvantages of the Database Approach Can be costly to implement additional hardware, software, storage, and network resources are required Can only run in certain operating environments may make it unsuitable for some system configurations Because it is so different from the file-oriented approach, the database approach requires training users may be inertia or resistance
  • 9. Internal Controls and DBMS The database management system (DBMS) stands between the user and the database per se. Thus, commercial DBMS’s (e.g., Access or Oracle) actually consist of a database plus… Plus software to manage the database, especially controlling access and other internal controls Plus software to generate reports, create data-entry forms, etc. The DBMS has special software to know which data elements each user is authorized to access and deny unauthorized requests of data.
  • 10. System Requests Elements of the Database Environment ‐‐Users Database System Development Administrator Process Applications User DBMS Transactions Programs Data Definition Host U Language Operating S Transactions User System Data E Programs Manipulation R Language S Transactions User Query Programs Language Physical Database User Queries
  • 11. Elements of the Database Environment ‐‐DBMS DBMS Features Program Development - user created applications Backup and Recovery - copies database Database Usage Reporting - captures statistics on database usage (who, when, etc.) Database Access - authorizes access to sections of the database Also… User Programs - makes the presence of the DBMS transparent to the user Direct Query - allows authorized users to access data without programming
  • 12. Data Definition Language (DDL) DDL is a programming language used to define the database per se. It identifies the names and the relationship of all data elements, records, and files that constitute the database. DDL defines the database on three viewing levels Internal view – physical arrangement of records (1 view) Conceptual view (schema) – representation of database (1 view) User view (subschema) – the portion of the database each user views (many views)
  • 14. Data Manipulation Language (DML) DML is the proprietary programming language that a particular DBMS uses to retrieve, process, and store data to / from the database. Entire user programs may be written in the DML, or selected DML commands can be inserted into universal programs, such as COBOL and FORTRAN. Can be used to ‘patch’ third party applications to the DBMS
  • 15. Query Language The query capability permits end users and professional programmers to access data in the database without the need for conventional programs. Can be an internal control issue since users may be making an ‘end run’ around the controls built into the conventional programs IBM’s structured query language (SQL) is a fourth-generation language that has emerged as the standard query language. Adopted by ANSI as the standard language for all relational databases
  • 17. Database Conceptual Models Refers to the particular method used to organize records in a database A.k.a. “logical data structures” Objective: develop the database efficiently so that data can be accessed quickly and easily There are three main models: hierarchical (tree structure) network relational Most existing databases are relational. Some legacy systems use hierarchical or network databases.
  • 18. The Relational Model The relational model portrays data in the form of two dimensional ‘tables’. Its strength is the ease with which tables may be linked to one another. A major weakness of hierarchical and network databases Relational model is based on the relational algebra functions of restrict, project, and join.
  • 19. Relational Algebra RESTRICT – filtering out rows, PROJECT – filtering out columns, such as the dark blue such as the light blue JOIN – build a new table or data set from multiple existing tables X1 Y1 Y1 Z1 X1 Y1 Z1 X2 Y2 Y2 Z2 X2 Y2 Z2 X3 Y1 Y3 Z3 X3 Y1 Z1
  • 20. Associations and Cardinality Association – the labeled line connecting two entities or tables in a data model Describes the nature of the between them Represented with a verb, such as ships, requests, or receives Cardinality – the degree of association between two entities The number of possible occurrences in one table that are associated with a single occurrence in a related table Used to determine primary keys and foreign keys
  • 21. “Crow’s Feet” Cardinalities (1:0,1) (1:1) (1:0,M) (1:M) (M:M)
  • 22. Properly Designed Relational Tables Each row in the table must be unique in at least one attribute, which is the primary key. Tables are linked by embedding the primary key into the related table as a foreign key. The attribute values in any column must all be of the same class or data type. Each column in a given table must be uniquely named. Tables must conform to the rules of normalization, i.e., free from structural dependencies or anomalies.
  • 23. Three Types of Anomalies Insertion Anomaly: A new item cannot be added to the table until at least one entity uses a particular attribute item. Deletion Anomaly: If an attribute item used by only one entity is deleted, all information about that attribute item is lost. Update Anomaly: A modification on an attribute must be made in each of the rows in which the attribute appears. Anomalies can be corrected by creating additional relational tables.
  • 24. Advantages of Relational Tables Removes all three types of anomalies Various items of interest (customers, inventory, sales) are stored in separate tables. Space is used efficiently. Very flexible – users can form ad hoc relationships
  • 25. The Normalization Process A process which systematically splits unnormalized complex tables into smaller tables that meet two conditions: all nonkey (secondary) attributes in the table are dependent on the primary key all nonkey attributes are independent of the other nonkey attributes When unnormalized tables are split and reduced to third normal form, they must then be linked together by foreign keys.
  • 26. Steps in Normalization Unnormalized table with repeating groups Remove repeating groups First normal form 1NF Remove partial dependencies Second normal form 2NF Remove transitive Third normal dependencies form 3NF Remove remaining Higher normal anomalies forms
  • 27. Accountants and Data Normalization Update anomalies can generate conflicting and obsolete database values. Insertion anomalies can result in unrecorded transactions and incomplete audit trails. Deletion anomalies can cause the loss of accounting records and the destruction of audit trails. Accountants should understand the data normalization process and be able to determine whether a database is properly normalized.
  • 28. Six Phases in Designing Relational  Databases 1. Identify entities • identify the primary entities of the organization • construct a data model of their relationships 2. Construct a data model showing entity associations • determine the associations between entities • model associations into an ER diagram
  • 29. Six Phases in Designing Relational  Databases 3. Add primary keys and attributes • assign primary keys to all entities in the model to uniquely identify records • every attribute should appear in one or more user views 4. Normalize and add foreign keys • remove repeating groups, partial and transitive dependencies • assign foreign keys to be able to link tables
  • 30. Six Phases in Designing Relational  Databases 5. Construct the physical database • create physical tables • populate tables with data 6. Prepare the user views • normalized tables should support all required views of system users • user views restrict users from have access to unauthorized data
  • 31. Distributed Data Processing (DDP) Data processing is organized around several information processing units (IPUs) distributed throughout the organization. Each IPU is placed under the control of the end user. DDP does not always mean total decentralization. IPUs in a DDP system are still connected to one another and coordinated. Typically, DDP’s use a centralized database. Alternatively, the database can be distributed, similar to the distribution of the data processing capability.
  • 32. Distributed Data Processing Central Centralized Site Database Site A Site B Site C
  • 33. Centralized Databases in DDP  Environment The data is retained in a central location. Remote IPUs send requests for data. Central site services the needs of the remote IPUs. The actual processing of the data is performed at the remote IPU.
  • 34. Advantages of DDP Cost reductions in hardware and data entry tasks Improved cost control responsibility Improved user satisfaction since control is closer to the user level Backup of data can be improved through the use of multiple data storage sites
  • 35. Disadvantages of DDP Loss of control Mismanagement of resources Hardware and software incompatibility Redundant tasks and data Consolidating incompatible tasks Difficulty attracting qualified personnel Lack of standards
  • 36. Data Currency Occurs in DDP with a centralized database During transaction processing, data will temporarily be inconsistent as records are read and updated. Database lockout procedures are necessary to keep IPUs from reading inconsistent data and from writing over a transaction being written by another IPU.
  • 37. Distributed Databases: Partitioning Splits the central database into segments that are distributed to their primary users Advantages: users’ control is increased by having data stored at local sites transaction processing response time is improved volume of transmitted data between IPUs is reduced reduces the potential data loss from a disaster
  • 38. The Deadlock Phenomenon Especially a problem with partitioned databases Occurs when multiple sites lock each other out of data that they are currently using One site needs data locked by another site. Special software is needed to analyze and resolve conflicts. Transactions may be terminated and restarted.
  • 39. The Deadlock Phenomenon Locked A, waiting for C Locked E, waiting for A A,B E, F C,D Locked C, waiting for E
  • 40. Distributed Databases: Replication The duplication of the entire database for multiple IPUs Effective for situations with a high degree of data sharing, but no primary user Supports read-only queries Data traffic between sites is reduced considerably.
  • 41. Concurrency Problems and Control  Issues Database concurrency is the presence of complete and accurate data at all IPU sites. With replicated databases, maintaining current data at all locations is difficult. Time stamping is used to serialize transactions. Prevents and resolves conflicts created by updating data at various IPUs
  • 42. Distributed Databases and the  Accountant The following database options impact the organization’s ability to maintain database integrity, to preserve audit trails, and to have accurate accounting records. Centralized or distributed data? If distributed, replicated or partitioned? If replicated, totally or partially replication? If partitioned, what allocation of the data segments among the sites?