Unit02 - Software Analysis And Design
Data Modeling
Software Engineering
Diploma in Computer/IT Engineering,
Gujarat Technological University, Gujarat, India
3. Data Modeling
Def:
“Process used to define and analyze data
requirements of a software.”
What?
Data objects: to be processed by system
Attributes: that describe data objects
Relationships: among data objects
To represent: ER Diagram
Outcome: Database
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4. Data Objects
Def:
“Any composite data/information that is used
(understood) by a software.”
Example: Student; Not only student name
Can be –
External entity (Emp, Cust, Supp); Thing (Bill, Order)
A Role (Admin, Manager)
Organization Unit (Dept); Place (Branch of a Bank)
Structure (File)
Data objects are related to each other
Encapsulates data only; No reference to
Operations
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5. Attributes
Def:
“Properties of data objects”
Example:
Student: id, name, add, city, c_no, email
Can be used to –
Name an instance of the data object: student name
Describe the instance: student id, add, city
Make reference to another instance in another table:
some foreign key (bname in Account table)
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7. Cardinality
Concept:
“Represents no. of occurrences of an object that can be
related to no. of occurrences of another object.”
Types:
One-to-One
One-to-Many, or, Many-to-One
Many-to-Many
Notation:
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ACC Belongs BRANCH
8. Modality
Concept:
“Represents participation of objects into relationship”
1: Participation in Relationship is Mandatory Total
0: Participation in Relationship is Optional Partial
Example:
Customer borrows Loan
Notation:
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CUSTOMER Borrows Loan