Use Case and Relational Database Modeling

•«includes» or «uses» relationship

Common subroutine

•Use case calling services of _____ which itself becomes additional use case

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major/minor cases

Notation of « Includes » Relationships:

•Relationship denoted by connecting line with ____

•Direction of the arrow indicates ___

fully developed description

is the most formal method for documenting a use case.

•you increase the probability that you thoroughly understand the business processes and the ways the system must support developers.

•To create a comprehensive, robust system that truly meets users’ needs, you must understand the detailed steps of each use case.

use case

Internally, a ____ includes a whole sequence of steps to complete a business process.

name

Name of the Use Case

scenario

Use case instances or several variations of the business steps exist within a single use case Example: Create Customer account. Create Online/By Phone/by Mail/by Walk-in Customer.

triggering event

identifies the event that triggers the use case

actors

always outside the automation boundary of the system but may be part of the manual portion of the system

related use case

identifies other use cases and the way they are related to this use case

preconditions

identify what the state of the system must be for the use case to begin, including what objects must already exist, what information must be available, and even the condition of the actor prior to beginning the use case.

postconditions

identify what must be true upon completion of the use case. Most important, they indicate what new objects are created or updated by the use case and how objects need to be associated. They are important for two reasons. First, they form the basis for stating the expected results for test cases that will be used for testing the use case after it is implemented.

flow of activities

describes the detailed ____ of the use case. The item numbers help identify the sequence of the steps.

exception conditions

describes the alternative activities and _______. The numbering also helps tie the exceptions to specific steps in the flow of activities.

E-R model

•expressed in terms of entities in the business environment, the relationships (or associations) among those entities, and the attributes (or properties) of both the entities and their relationships

•most commonly used conceptual model

conceptual data modeling

•about understanding the organization—getting the right requirements.

Entity Relationship Diagrams

•are representation of ER Model.

business rules

•defines relationships and cardinalities.

entity

rectangle

an entity is a person, place, thing, rectangle or event about which an organization wishes to maintain data

attribute

ellipse

characteristic of an entity

relationship

diamond

a natural association between the instances of one or more entities

cardinality

•the number of instances that is associated between a pair of entity types

•the cardinality of the association from A to B is the maximum number of occurrences of B that can be associated with A

•a pair of associations can exist between any two entities

relationship

•a logical link between entities based on how they interact

Entity-Relationship Diagrams

Cardinality notation

1

•One-to-one relationship (1:1)

•One-to-many relationship (1:M)

•Many-to-many relationship (M:N)

2

•Crow’s foot notation

•Unified Modeling Language (UML)

relational design model

•about creating stable database structures.

•model represents data in the form of tables or a shorthand notation

data structures

Data are organized in the form of tables, with rows and columns.

data manipulation

•Powerful operations (using the SQL language) are used to manipulate data stored in the relations.

data integrity

The model includes mechanisms to specify business rules that maintain the integrity of data when they are manipulated.

Domain Class: Associative Class

•An association that is also treated as a class; often required in order to capture attributes for the association

•Example: one course section has many course enrollments—each with its own grade—and each course enrollment applies to one specific student.

Generalization/Specialization Relationships

•a type of hierarchical relationship in which subordinate classes are subsets of objects of the superior classes; an inheritance hierarchy

Inheritance

•the concept that specialization classes inherit characteristics of the generalization class

abstract class

a class that only exists so subclasses can inherit from it. There is never an actual object simply called a Sale.

Sale is in italic

concrete class

a class that does have actual objects.

Each sale must be one of the three subclasses.

whole-part relationships

relationships between classes in which one class is a part or a component portion of another class

aggregation

aggregate

•a type of whole-part relationship in which the component parts also exist as individual objects apart from the ____

composition

a type of whole-part relationship in which the component parts cannot exist as individual objects apart from the total ___