RelationalDBDesign
SiteMap
Database Analysis
Database Design
Extended DB Features
Oracle SQL Extensions
ER Diagrams
«Prev
Next»
Database Design
Database Structure
Relational Database Model
Relationally Complete
Relational Completeness
Database Structure
Linking Database Tables
SQL in RDBMS
Create Table SQL
DBMS
Database Change Management
Relational DB Structure
Database Life Cycle
Database Design Strategy
Subject Approach DB Design
Design Subject
Application Approach Design
Schema Architecture
Three Schema Arch
DBLC Design Stages
Post Design Stages
Design Tools
DB Design Strategy Conclusion
Requirements Analysis
Requirements Analysis
Define Business Objects
BO Characteristics
Business Rules Importance
Interview Data Users
Data Flow Diagram
Creating User Views
Calculated Fields
Requirements Documentation
Requirements Analysis Conclusion
Attributes and Entities
Entities Conceptual Model
Store Entity Values
Rules for Creating Identifiers
Entity Instances
Attribute Domains Types
Multivalued Attribute
Multi-Valued Attributes
Multivalued Attribute(resolve)
Entity Attribute Constraints
Module Summary
ER Diagrams
ERD Concept
Three Relationship Types
One to One Relationships
Identify one To One
One to many Relationships
Identify One to Many
Define many To Many
Identify Many To Many
Many to Many Challenges
Convert m:n to 1:n
Mandatory Optional Relationship
Optional Participation Relationships
ERD Conclusion
ERD Conventions
ER Diagram
Three Model Types
idef1x Crowsfoot Chen Models
Entity Attribute Relationship
ER Diagram Types
Crow's Foot Notation
DB Participation Types
Interview End- Users
Verbalize ER Diagram
ER diagram model Types
Resolving many-to-many Relationships - Exercise
Objective:
Convert a many-to-many relationship into two "one-to-many" relationships.
Exercise Scoring
This exercise is worth a total of 30 points. You will receive up to 10 points for correctly creating each attribute of the composite entity as described below.
Background and Overview
In the preceding lesson, you learned that
many-to-many relationships
are resolved by breaking down each M:N relationship into two 1:N relationships. This is achieved by creating a composite entity whose only function is to represent the link between the other two entities. You also learned that the composite entity has no key attribute of its own; rather, it accepts the key attributes from the other two entities to form a composite key attribute.
Instructions
The Stories on CD case study has one many-to-many relationship: the ORDER:CD relationship. Your task is to resolve the ORDER:CD relationship. The two entities are illustrated below, complete with the attributes you will need to complete this exercise.
Two Entities ORDER and CD
Please name the composite entity you create LINE ITEM. Your answer should be in the following format:
ORDER
attribute
attribute
etc.
LINE ITEM
attribute
attribute
etc.
CD
attribute
attribute
etc.
Hints
When a composite entity is created to link two other entities, it sometimes makes sense to move some non-key attributes out of the other two entities and into the composite entity. Keep this in mind when you populate the composite entity with attributes.
Submitting your exercise
Type or paste your answers into the text box below, then click
Submit
to submit your result and view a results page.