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Analyzing System Using Analyzing System Using Data DictionariesData Dictionaries

Computer System:

1. Data Dictionary

2. Data Dictionary Categories

3. Creating Data Dictionary

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Data DictionaryData Dictionary

a referencea reference data about datadata about data metadatametadata keep clean datakeep clean data

– reduce redundancyreduce redundancy collect and coordinates data termscollect and coordinates data terms provide documentationprovide documentation

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Data RepositoryData Repository

A larger collection of project informationA larger collection of project information

May contain:May contain: information about datainformation about data procedural logic and use caseprocedural logic and use case I/O designI/O design data relationshipsdata relationships project requirements and deliverablesproject requirements and deliverables project management informationproject management information

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Information About DataInformation About Data data data flowflow data data storesstores record record structuresstructures elementselements entitiesentities messagesmessages

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I/O DesignI/O Design

ScreenScreen ReportReport

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Data RelationshipsData Relationships

data data structuresstructures linkslinks between data between data

structuresstructures

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Project Management Project Management InformationInformation

delivery delivery schedulesschedules achievementsachievements issuesissues needed resolving needed resolving project project usersusers

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Data Dictionary CategoriesData Dictionary Categories

Data flowsData flows data structuresdata structures data elementsdata elements data storesdata stores

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Data FlowsData FlowsDefining the data flows:Defining the data flows: IDID UniqueUnique descriptive name descriptive name general general descriptiondescription sourcesource destinationdestination recordrecord entering or leaving entering or leaving name of the name of the data structuredata structure volume per volume per unit of timeunit of time further comments and notations further comments and notations

areaarea

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Data StructuresData Structures

Data structures are usually described:Data structures are usually described: using algebraic notationusing algebraic notation = means “is composed of”= means “is composed of” + means “and”+ means “and” { } indicate repetitive elements{ } indicate repetitive elements [ ] represent an either/or situation[ ] represent an either/or situation ( ) represent an optional element( ) represent an optional element

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Data Structure SyntaxData Structure Syntax

Data Structure (table)Data Structure (table)– collection of structural recordscollection of structural records

Structural Record (row)Structural Record (row)– collection of component elementscollection of component elements

component elements (column)component elements (column)– collection of characterscollection of characters

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Data Structure ExampleData Structure Example Customer Name =Customer Name =

– First Name +First Name +– (Middle Initial) +(Middle Initial) +– Last NameLast Name

Method of Payment =Method of Payment =– [Check | Charge | Money Order][Check | Charge | Money Order]

Credit Card Type =Credit Card Type =– [American Express | MasterCard | Visa][American Express | MasterCard | Visa]

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Logical Data StructuresLogical Data StructuresThe data elements used by users such asThe data elements used by users such as

– namename– addressaddress– balance duebalance due– telephone telephone

Logical design stage Logical design stage – reflect user’s view of the system reflect user’s view of the system

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Physical Data StructurePhysical Data Structure

Physical data structure includes Physical data structure includes additionaladditional elements used by the elements used by the systemsystem– KeyKey fields fields– codescodes identify the status of master identify the status of master

recordsrecords– transactiontransaction codes codes

used to identify types of recordsused to identify types of records

– Repeating group entries Repeating group entries countcount– LimitsLimits on repeated group on repeated group– A password for A password for securitysecurity

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Data ElementsData ElementsEach data element should be defined Each data element should be defined

onceonce1.1. Element IDElement ID2.2. Name of elementName of element3.3. AliasesAliases4.4. A short descriptionA short description5.5. Base or derived elementBase or derived element6.6. lengthlength7.7. data typedata type8.8. I/O formatI/O format9.9. validation criteria for accuracyvalidation criteria for accuracy10.10. default valuedefault value11.11. additional comment or remarks areaadditional comment or remarks area

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Data StoresData StoresData store description formData store description form data store IDdata store ID namename alias for the tablealias for the table short descriptionshort description file file typetype: computer or manual: computer or manual formatformat : database, indexed, sequential, or : database, indexed, sequential, or

directdirect maximum and average number of recordsmaximum and average number of records file or data set namefile or data set name commentcomment

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Creating Data DictionaryCreating Data Dictionary

Analyzing Input and OutputAnalyzing Input and Output Developing Data StoreDeveloping Data Store

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I/O Analysis FormI/O Analysis FormThe form may containsThe form may contains Descriptive nameDescriptive name User contactUser contact Input or output file typeInput or output file type Format of data flowFormat of data flow

– reportreport– screenscreen– undeterminedundetermined

ElementsElements– sequencesequence– base or derived database or derived data– etc.etc.

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Data Flow / Data StoreData Flow / Data Store

Data flowData flow– data in motiondata in motion

data storedata store– data at restdata at rest

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Data Flow ExampleData Flow Example

Employee

Paycheck

Hours worked 2.1

GeneralProcessBBB 1

2.2

GeneralProcessBBB 2

D3 Employee DS

Employee Record

Current pay

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Data Dictionary EntriesData Dictionary Entries

Employee

Paycheck

Hours worked 2.1

GeneralProcessBBB 1

2.2

GeneralProcessBBB 2

D3 Employee DS

Employee Record

Current pay amount

Hours Worked =

Employee ID +

Hours

Employee Record =

Employee ID +

Personal Information +

Wage Information

Employee paycheck =

Employee ID +

Employee Name +

Address +

Current pay amount +

Pay Date

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Using the Data DictionaryUsing the Data Dictionary

may be used to createmay be used to create screensscreens reportsreports formsforms

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Extensible Markup Extensible Markup LanguageLanguage

Similar to HTMLSimilar to HTML HTML HTML

– formatting documentformatting document XMLXML

– data sharing between different systemsdata sharing between different systems– a way to a way to

define, define, sort, sort, filter, and filter, and translate data into a universal data languagetranslate data into a universal data language