Question

You are hired to design a database for a fitness center. As the fitness center is expanding with more than one branch, they want to create a database to keep track of its customers, facilities and employees. Each branch has a unique id and address (building number, street, district, and city). A branch may have more than one facility (e.g. swimming pool, spa, etc.). Each facility must belong to only one branch, and the information for a facility is name and fees. In addition, each fitness branch offers different classes (such as Yoga, Pilates, Zumba, etc.). All classes should be led by at most one trainer, who is an employee.

Employees must work at one and only one branch. Each employee has an id, name, address (building number, street, district, and city) and can have multiple phone numbers. An employee can only be an admin, managing the facility or working as a clerk, or a trainer. An employee cannot be a trainer and an admin because the trainer id compensated an hourly wage while an admin staff paid a monthly salary. Trainers can train individual customers at different time sessions.

A customer must register at one branch. Each customer has a membership number, name (stored as first name and last name), email, and only one phone number. A customer can join more than one class or uses any number of facilities. A customer may also decide to be trained by at most one personal trainer.


Given the above description: 1. Draw an ERD for the database, identifying the following: a. All the entities, attributes and relationships b. Primary key and (discriminator in weak entity, if any). Don’t forget each entity has to have PK. c. Participation and cardinality constraints. (Explain your choices for two constraints- i.e. identify the words the guided your decision) d. Specialization and completeness constraints (if there is an ISA relationship).

2. Write a schema for two entities and two relationships of your choice. Remember, sometimes a relationship is better not be represented in a separate schema; if this is the case with your chosen relationship explain what you will do.

Answer 1

This is an ER diagram for fitness centre with more facilities. There are more attributes included than given in the question. The schema describes two entities i.e member entity and trainer entity.The above diagram also gives information about entities related to two relationships i.e manage and has relationship.