Data dictionaries

What is Data Dictionary?

05/02/23AITS-MCA (Kiran Ajudiya)

1

Data Dictionary is : a reference data about data (metadata) keep clean data

reduce redundancy collect and coordinates data

terms provide documentation

Why Data Dictionary?1. Validate the data flow diagram for

completeness and accuracy.2. Provide a starting point for

developing screen and reports.3. Determining the contents of data

stored in files4. Develop the logic for data flow

diagram processes.5. Create XML.


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Data Repository


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A larger collection of project informationMay contain: information about data procedural logic and use case I/O design data relationships project requirements and deliverables project management information

Information About Data


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data flow data stores record structures elements entities messages

I/O Design


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Screen Report

Data Relationships


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Data structures Links between data

structures

Project Management Information


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delivery schedules achievements issues needed resolving project users

Data Dictionary Categories


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Data flows data structures data elements data stores

Data Flows


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Defining the data flows: ID Unique descriptive name general description source of data flow destination of data flow record entering or leaving name of the data structure volume per unit of time further comments and notations

area

05/02/23AITS-MCA (Kiran Ajudiya)10

Data Structures


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Data structures are usually described: using algebraic notation = means “is composed of”

/collected + means “and” { } indicate repetitive elements [ ] represent an either/or situation ( ) represent an optional element

Data Structure Syntax


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Data Structure (table) collection of structural

records Structural Record (row)

collection of component elements

component elements (column) collection of characters

Data Structure Example


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Customer Name = First Name + (Middle Initial) + Last Name

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

Credit Card Type = [American Express | MasterCard |

Visa]

Logical Data Structures


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The data elements used by users such as name address balance due telephone

Logical design stage reflect user’s view of the system

Physical Data Structure


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Physical data structure includes additional elements used by the system Key fields codes identify the status of master records transaction codes

used to identify types of records Repeating group entries count Limits on repeated group A password for security


Data Elements


17 Each data element should be defined once

1. Element ID2. Name of element3. Aliases4. A short description5. Base or derived element6. length7. data type8. I/O format9. validation criteria for accuracy10. default value11. additional comment or remarks area


Data Stores


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Data store description form data store ID name alias for the table short description file type: computer or manual format : database, indexed, sequential, or

direct maximum and average number of records file or data set name comment


Creating Data Dictionary


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Analyzing Input and Output Developing Data Store

I/O Analysis Form


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The form may contains Descriptive name User contact Input or output file type Format of data flow

report screen undetermined

Elements sequence base or derived data

Data Flow / Data Store


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Data flow data in motion

data store data at rest

Data Flow Example


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Employee

Paycheck

Hours worked 2.1

GeneralProcessBBB 1

2.2

GeneralProcessBBB 2

D3 Employee DS

Employee Record

Current pay

Data Dictionary Entries


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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

Using the Data Dictionary


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may be used to create

screens reports forms

Extensible Markup Language


27 Similar to HTML HTML

formatting document XML

data sharing between different systems a way to

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

language

Date post:	13-Apr-2017
Category:	Education
Upload:	kiran-ajudiya
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Data dictionaries

Education