1. System Analysis and Design
- Mr. Ahmad Al-Ghoul
In this sequence we will discuss the data dictionary and how the analyst can use it to document data elements and data structures

2. System Analysis and Design System Analysis
Learning Objectives
Describe how a data dictionary is used and what it contains
Create a data dictionary entries for data elements
Create a data dictionary entries for data structure or record
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System Analysis and Design System Analysis

3. System Analysis and Design System Analysis
Data Dictionary
A data dictionary, or data repository, is a central storehouse of information about the system’s data
A data dictionary is created when the system is developed, and is updated constantly as the system is implemented, operated, and maintained
An analyst uses the data dictionary to collect, document, and organize specific facts about the system
In addition to describing each data element, data structure, data flow, data store, entity, and process, the data dictionary documents the relationships among these components
Without a data dictionary the development of large systems becomes difficult.
The data dictionary is an effective solution to the problem of complicated nature. The main purpose of a data dictionary is to provide a source of reference in which the analyst , the user, the designer can look up & find out it’s content and any other relevant information.
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System Analysis and Design System Analysis

4. System Analysis and Design System Analysis
Data Dictionary
Data Elements
A data element, also called a data item or field, is the smallest piece of data that has meaning
Data elements are pieces of data, which need not be broken further.
Data elements are combined into records, also called data structures
A record is a meaningful combination of related data elements that is included in a data flow or retained in a data store
Data elements can describe files, data flows, or processes.
Often a data element is self defining such as Student name, enrolment no.
Each element should be defined once in the data dictionary
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System Analysis and Design System Analysis

5. System Analysis and Design System Analysis
Data Dictionary
Documenting the Data Elements
You must document every data element in the data dictionary
The objective is to provide clear, comprehensive information about the data and processes that make up the system
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System Analysis and Design System Analysis

6. System Analysis and Design System Analysis
Data Dictionary
Documenting the Data Elements
The following attributes usually are recorded and described
Data element name or label: the standard name for the data element ; it should be meaningful to users.
Type and length: type refers to whether the data element contains numeric, char, date values. Length is the maximum number of char data element or the maximum number of digits and numbers of decimal positions for numeric data elements.
Output format: the arrangement of the data element when users see it printed in reports or displayed on the screen
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System Analysis and Design System Analysis

7. System Analysis and Design System Analysis
Data Dictionary
Documenting the Data Elements
Default values: the value for the data element if a value otherwise is not entered for it.
Prompt, column header, field caption: the default display screen prompt or report column heading when the information system outputs the data elements.
Source: the specification for the rogation point for the data elements values, the source could be a specific form , a department or outside organization, anther information system or the result of a calculation
Security: identification for the individual or department that has access or update privileges for each data elements.
Responsible users: identification of the users responsible for entering and changing values for the data elements
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System Analysis and Design System Analysis

8. System Analysis and Design System Analysis
Data Dictionary
Documenting the Data Elements
Acceptable values: specification of the data element domain which, is the set of values permitted for the data element; these values either can be specifically listed or referenced in a table, or selected from a specified range of values. You also would indicate if a value for the data element is optional.
Derivation formula: if the data element value is the result of a calculation, then you show the formula for the data element, including significant digits and rounding operations; if any
Description or comments: part of the data element documentation that allows you to provide additional definitions, descriptions or notes
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System Analysis and Design System Analysis

9. System Analysis and Design System Analysis
Data Dictionary
Data structure or record
Data structures or records are a group of smaller structures and elements
An algebraic notation is used to represent the data structure
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System Analysis and Design System Analysis

10. System Analysis and Design System Analysis
Data Dictionary
Data structure or record
Algebraic Notation
The symbols used are
Equal sign, meaning “consists of”
Plus sign, meaning "and”
Braces {} meaning repetitive elements, a repeating element or group of elements
Brackets [] for an either/or situation. Either one element may be present or anther, but not both
The elements listed inside are mutually exclusive
Parentheses () for an optional element
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System Analysis and Design System Analysis

11. System Analysis and Design System Analysis
Data Dictionary
Data structure or record
Each structure or group of elements is analyzed
Each element should be analyzed by asking the following questions:
A. Are there many of the field?
If the answer is yes, indicate that the field is a repeating field using the { } symbols
B. Is the element mutually exclusive of another element?
If the answer is yes, surround the two fields with the [ | ] symbols
C. Is the field an optional entry or optionally printed or displayed?
If so, surround the field with parenthesis ( )
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System Analysis and Design System Analysis

12. System Analysis and Design System Analysis
Data Dictionary [2]
Data Structure or record Example
Customer Order = Customer Number +
Customer Name +
Address +
Telephone +
Catalog Number +
Order Date +
{Available Order Items} +
Merchandise Total +
(Tax) +
Shipping and Handling +
Order Total +
Method of Payment +
(Credit Card Type) +
(Credit Card Number) +
(Expiration Date)
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System Analysis and Design System Analysis

13. System Analysis and Design System Analysis
Data Dictionary
Documenting the data structure or record
Record or data structure name: the data structure or record name as it appears in the related data flows and data stores
Definition or description: a brief definition
Alternate name(s): aliases for the data structure or record name
Attributes: a list of all the data elements included in the data structure or record
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System Analysis and Design System Analysis

14. System Analysis and Design System Analysis
Sequence Summary
The data dictionary is the central documentation tool for structured analysis
A data dictionary is created when the system is developed, and is updated constantly as the system is implemented, operated, and maintained
An analyst uses the data dictionary to collect, document, and organize specific facts about the system
Data elements are pieces of data, which need not be broken further.
You must document every data element in the data dictionary
Data elements are combined into records, also called data structures
An algebraic notation is used to represent the data structure
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System Analysis and Design System Analysis

15. System Analysis and Design System Analysis
Sequence Summary
In this Sequence we have
Describe how a data dictionary is used and what it contains
Defined the term data element
Create a data dictionary entries for data elements
Defined the term data structure or record
Explained how to use algebraic notation in documenting the data structure
Create a data dictionary entries for data structure or record
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System Analysis and Design System Analysis

16. System Analysis and Design System Analysis
Reference
[1] System Analysis and Design, Sixth Edition
Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt ,
Publisher: SHELLY CASHMAN SEWIES.
[2] system analysis and design, sixth edition
Authors: Kenneth E. Kendall and Julie E. Kendall
Publisher: Prentice Hall
[3] Modern Systems Analysis and Design Third Edition
Authors: Jeffrey A. Hoffer , Joey F. George, Joseph S. Valacich
Publisher: prentice hall
[4] System Analysis and Design, 3rd Edition
Authors: Dennis, Wixom, & Roth
Publisher: John Wiley & sons
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