- Ahmad Al-Ghoul Data design. 2 learning Objectives Explain data design concepts and data structures...

- Ahmad Al-Ghoul- Ahmad Al-Ghoul

Data designData design

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learning Objectiveslearning Objectives

Explain data design concepts Explain data design concepts and data structuresand data structures

Describe file processing Describe file processing systems and various types of systems and various types of filesfiles

Understand database systems Understand database systems and define the advantages of and define the advantages of a database management a database management system (DBMS)system (DBMS)

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Data Design ConceptsData Design Concepts Before constructing an information Before constructing an information

system, a systems analyst must system, a systems analyst must understand basic design concepts, understand basic design concepts, including data structures and the including data structures and the characteristics of file processing and characteristics of file processing and database systems, including Web-database systems, including Web-based database designbased database design

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Data Design ConceptsData Design Concepts

The data storage function manages The data storage function manages how data is stored and handled by how data is stored and handled by programs that run the systemprograms that run the system

Goals of data storage designGoals of data storage design Efficient data retrieval (good response Efficient data retrieval (good response

time)time) Access to the information users needAccess to the information users need

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Data Design ConceptsData Design Concepts Data StructuresData Structures

A framework for organizing and storing data A framework for organizing and storing data Data Structures consist of files or tables that Data Structures consist of files or tables that

are linked in various waysare linked in various ways A A filefile or or tabletable contains data about people, places or contains data about people, places or

events or any important data that the business must events or any important data that the business must kept information aboutkept information about

Depending on how the system’s file and tables are Depending on how the system’s file and tables are organized and linked, an (IS) is called either organized and linked, an (IS) is called either

File-oriented systemFile-oriented system: also called a file processing : also called a file processing system, stores and manages data in one or more system, stores and manages data in one or more separate files. separate files.

Database systemDatabase system: consists of linked data files, also : consists of linked data files, also called tables, that form an overall data structure. called tables, that form an overall data structure. Compared to file processing, a database environment Compared to file processing, a database environment offers greater flexibility and efficiency. offers greater flexibility and efficiency.

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Data Design ConceptsData Design Concepts Overview of File ProcessingOverview of File Processing

Companies mainly use file processing to Companies mainly use file processing to handle large volumes of structured data on handle large volumes of structured data on a regular basisa regular basis

File processing design approach was well File processing design approach was well suited to mainframe hardware and batch suited to mainframe hardware and batch inputinput

File processing design is less common File processing design is less common today, file processing can be more efficient today, file processing can be more efficient and cost less than a DBMS in certain and cost less than a DBMS in certain situationssituations

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Overview of File ProcessingOverview of File Processing File Processing AdvantagesFile Processing Advantages

SimplicitySimplicity: the design of file processing is more : the design of file processing is more simple than designing Databasesimple than designing Database

EfficiencyEfficiency: file processing cost less and can be : file processing cost less and can be more speed than Databasemore speed than Database

CustomizationCustomization: you can customize file processing : you can customize file processing more easily and efficiently than Database more easily and efficiently than Database because files are related with the application because files are related with the application and it have all the data needed for that and it have all the data needed for that applicationapplication

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Overview of File ProcessingOverview of File Processing Potential problems Potential problems

Data redundancyData redundancy: occurs when data common to two or : occurs when data common to two or more information systems is stored in several places. more information systems is stored in several places. Data redundancy requires more storage space, and Data redundancy requires more storage space, and maintaining and updating data in several locations is maintaining and updating data in several locations is expensive. expensive.

Data integrityData integrity: Refers to the validity of data. Data : Refers to the validity of data. Data integrity can be compromised in a number of ways: integrity can be compromised in a number of ways: human errors when data is entered, errors that occur human errors when data is entered, errors that occur when data is transmitted from one computer to another, when data is transmitted from one computer to another, software bugs or viruses, hardware malfunctions, such as software bugs or viruses, hardware malfunctions, such as disk crashes and natural disasters, such as fires and disk crashes and natural disasters, such as fires and floods. floods.

Rigid data structureRigid data structure: A data structure that is hard to work : A data structure that is hard to work with and inflexible. File-processing is rigid when with and inflexible. File-processing is rigid when compared to a typical database management system. compared to a typical database management system.


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Uses various types of filesUses various types of files Master fileMaster file: In a typical file processing environment, a : In a typical file processing environment, a

master file stores relatively permanent data about an master file stores relatively permanent data about an entity. For example, a PRODUCT master file might entity. For example, a PRODUCT master file might contain one logical record for each product a company contain one logical record for each product a company sells. sells.

Table fileTable file: contains reference data used by the (IS). As : contains reference data used by the (IS). As with master files, table files are relatively static and with master files, table files are relatively static and are not updated by the (IS). Examples include tax are not updated by the (IS). Examples include tax tables and postage rate tablestables and postage rate tables

Transaction file: In a typical file processing Transaction file: In a typical file processing environment, a transaction file stores records that environment, a transaction file stores records that contain day-to-day business and operational data. A contain day-to-day business and operational data. A transaction file is an input file that updates a master transaction file is an input file that updates a master file; after the update is completed, the transaction file file; after the update is completed, the transaction file has served its purpose. has served its purpose.

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Uses various types of filesUses various types of files Work file – scratch file: In a typical file processing Work file – scratch file: In a typical file processing

environment, a work file is a temporary file created environment, a work file is a temporary file created by an information system for a single task. Most often by an information system for a single task. Most often a work file is created by one process in the a work file is created by one process in the information system and used by another process information system and used by another process within the same system. Work files also are called within the same system. Work files also are called scratch files. scratch files.

Security file: Sequence codes are numbers or letters Security file: Sequence codes are numbers or letters assigned in a specific order. Sequence codes contain assigned in a specific order. Sequence codes contain no additional information other than an indication of no additional information other than an indication of order of entry into a system. order of entry into a system.

History file: In a typical file processing environment, a History file: In a typical file processing environment, a history file is a file copy created and saved for history file is a file copy created and saved for historical or archiving purposes. New history files, historical or archiving purposes. New history files, unlike new security files, do not replace the old files. unlike new security files, do not replace the old files.

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Data Design ConceptsData Design Concepts Example of File Processing of an auto repair shopExample of File Processing of an auto repair shop

Example of an auto repair shop that uses two separate file-oriented systems: a Job Records System (with a JOB data file) and an Employee Records System (with a MECHANIC data file). Notice that three items of information must be duplicated in both data files.

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Overview of Database SystemsOverview of Database Systems Database: a collection of groupings of Database: a collection of groupings of

information that relate to each other in some information that relate to each other in some way.way.

A properly design database system offers a A properly design database system offers a solution to the problems of file processingsolution to the problems of file processing

Provides an overall framework that avoids data Provides an overall framework that avoids data redundancy and supports a real-time, dynamic redundancy and supports a real-time, dynamic environmentenvironment

In a Database environment several systems can In a Database environment several systems can be built and share a single databasebe built and share a single database

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Data Design ConceptsData Design ConceptsOverview of Database SystemsOverview of Database SystemsA typical database environment might consist of a database serving five separate business systems.

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Example of a database design for the auto repair shop that links two data tables and avoids duplication. Notice that the Mechanic No field provides a link between the two tables, and information can be accessed from either table.

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Data Design ConceptsData Design Concepts Overview of Database SystemsOverview of Database Systems

A A database management system (DBMS)database management system (DBMS) is a collection of tools, features, and is a collection of tools, features, and interfaces that enables users to add, interfaces that enables users to add, update, manage, access, and analyze the update, manage, access, and analyze the contents of a databasecontents of a database

The main advantage of a DBMS is that it The main advantage of a DBMS is that it offers timely, interactive, and flexible offers timely, interactive, and flexible data accessdata access

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AdvantagesAdvantages Scalability: Scalability means that a system can be Scalability: Scalability means that a system can be

expanded, modified, or downsized easily to meet the expanded, modified, or downsized easily to meet the rapidly changing needs of a business enterprise. Also rapidly changing needs of a business enterprise. Also known as extensibility. known as extensibility.

Better support for client/server systemsBetter support for client/server systems: In a : In a client/server system, processing is distributed client/server system, processing is distributed throughout an organization. Client/server systems throughout an organization. Client/server systems require the power and flexibility of database design. require the power and flexibility of database design.

Economy of scale: The inherent efficiency of high-Economy of scale: The inherent efficiency of high-volume processing on larger computers. Database volume processing on larger computers. Database design allows better utilization of hardware. If a design allows better utilization of hardware. If a company maintains an enterprise-wide database, company maintains an enterprise-wide database, processing is less expensive using a powerful mainframe processing is less expensive using a powerful mainframe server instead of using several smaller computers. server instead of using several smaller computers.

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AdvantagesAdvantages Flexible data sharingFlexible data sharing: Data can be shared across the : Data can be shared across the

enterprise, allowing more users to view the same enterprise, allowing more users to view the same information in different ways information in different ways

Enterprise-wide applicationEnterprise-wide application – database administrator – database administrator (DBA):(DBA): (DBA) typically manages a database (DBA) typically manages a database management system (DBMS). The DBA assesses management system (DBMS). The DBA assesses overall requirements and maintains the database for overall requirements and maintains the database for the benefit of the entire organization rather than a the benefit of the entire organization rather than a single department or user. single department or user.

Stronger standardsStronger standards: effective database : effective database administration helps ensure that standards for data administration helps ensure that standards for data names, formats, and documentation are followed names, formats, and documentation are followed uniformly throughout the organizationuniformly throughout the organization

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AdvantagesAdvantages Controlled redundancyControlled redundancy: because the data is stored in : because the data is stored in

a set of related tables, data items do not need to be a set of related tables, data items do not need to be duplicated in multiple locationsduplicated in multiple locations

Better securityBetter security: the DBA defines authorization : the DBA defines authorization procedures to ensure that only legitimate users can procedures to ensure that only legitimate users can access the database and can allow different users to access the database and can allow different users to have different levels of accesshave different levels of access

Increased programmer productivityIncreased programmer productivity: programmers do : programmers do not have to create the underlining file structure for not have to create the underlining file structure for the database, so they can concentrate on logical the database, so they can concentrate on logical designdesign

Data independenceData independence: systems that interact with a : systems that interact with a DBMS are relatively independent of how the physical DBMS are relatively independent of how the physical data is maintaineddata is maintained

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Data Design ConceptsData Design Concepts Database TradeoffsDatabase Tradeoffs

Because DBMSs are powerful, they Because DBMSs are powerful, they require more expensive hardware, require more expensive hardware, software, and data networks capable of software, and data networks capable of supporting a multi-user environmentsupporting a multi-user environment

More complex than a file processing More complex than a file processing systemsystem

Procedures for security, backup, and Procedures for security, backup, and recovery are more complicated and recovery are more complicated and criticalcritical

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Sequence SummarySequence Summary Files and tables contain data about people, places, things, Files and tables contain data about people, places, things,

or events that affect the information systemor events that affect the information system File processing systems, also called file-oriented systems, File processing systems, also called file-oriented systems,

manage data stored in separate files, including master files, manage data stored in separate files, including master files, table files, transaction files, work files, security files, and table files, transaction files, work files, security files, and history fileshistory files

A database consists of linked tables that form an overall A database consists of linked tables that form an overall data structuredata structure

A database management system (DBMS) is a collection of A database management system (DBMS) is a collection of tools, features, and interfaces that enable users to add, tools, features, and interfaces that enable users to add, update, manage, access, and analyze data in a databaseupdate, manage, access, and analyze data in a database

DBMS designs are more powerful and flexible than DBMS designs are more powerful and flexible than traditional file-oriented systemstraditional file-oriented systems

A database environment offers scalability, support for A database environment offers scalability, support for organization-wide access, economy of scale, data sharing organization-wide access, economy of scale, data sharing among user groups, balancing of conflicting user among user groups, balancing of conflicting user requirements, enforcement of standards, controlled requirements, enforcement of standards, controlled redundancy, effective security, flexibility, and data redundancy, effective security, flexibility, and data independenceindependence

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Sequence SummarySequence Summary

In this Sequence we haveIn this Sequence we have Distinguished between Distinguished between file processing file processing

system and database systemsystem and database system Explained the advantages and Explained the advantages and

disadvantages of file processing systemdisadvantages of file processing system Described the various types of files in Described the various types of files in

the file processing systemthe file processing system Defined the term data base Defined the term data base

management system (DBMS)management system (DBMS) Explained the advantages of database Explained the advantages of database

systemsystem Described the database tradeoffsDescribed the database tradeoffs

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ReferenceReference

[1] System Analysis and Design, Sixth [1] System Analysis and Design, Sixth EditionEdition

Authors: Gary B. Shelly, Thomas J. Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt Cashman and Harry J. Rosenblatt

Publisher: SHELLY CASHMAN Publisher: SHELLY CASHMAN SEWIES.SEWIES.

- Ahmad Al-Ghoul Data design. 2 learning Objectives Explain data design concepts and data structures...

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