Linking Database Tables
Database Management System
Database Life Cycle
DBLC Design Stages
3 Schema Architecture
Post Design Stages
Application Approach DB Design
Database Design Strategy
Business Rules Importance
Customer Order Shipment
Define Business Objects
Data Flow Diagram
Interview Data Users
Attributes and Entities
Entities Conceptual Model
Store Entity Values
Attribute Domains Types
Rules for Creating Identifiers
Three Relationship Types
Convert m:n to 1:n
One to One Relationships
Optional Participation Relationships
Mandatory Optional Relationship
Student Class Entities
Resolving many-to-many relationships - Exercise
Convert a many-to-many relationship into two "one-to-many" relationships.
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.
In the preceding lesson, you learned that
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.
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:
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
to submit your result and view a results page.