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Mandatory and Optional Participation - Exercise

Idenity Mandatory and optional relationships in an ERD diagram

Objective: Identify mandatory and optional relationships.

Exercise Scoring

This exercise is worth a total of 30 points. You will receive up to five points for correctly identifying the type of participation each entity belonging to Stories on CD, Inc. has within its relationships.


In the previous two lessons, you learned that every entity in a relationship has either mandatory or optional participation in its relationships. You also learned that the type of participation for a weak entity in a relationship is designated as optional, whereas a mandatory entity is in a mandatory relationship.


Now that you have established the types of relationships that exist for all the entities belonging to Stories on CD, Inc., the final step is to identify the type of participation each entity has within its relationships. One relationship has been analyzed for you: CUSTOMER:ORDER, outlined below:

  1. CUSTOMER:ORDER relationship
  2. CUSTOMER = mandatory entity in a mandatory relationship
  3. ORDER = weak entity in an optional relationship
Use the format outlined above to identify the types of participation each of the remaining entities has within it relationships.

Submitting your exercise

Type or paste your answers into the text box below, then click Submit button to submit your answer and view a results page.