Exercise: patients and blood samples

(Wayne Dick)

Consider enterprise of a medical clinic where we wish to track the level of various substances (for example, cholesterol or alcohol) in the blood of patients. For each blood sample that is taken from the patient, one test will be performed and the date of the sample, the substance tested, and the measured level of that substance will be recorded in a database.

Model the information provided by completing the following steps.

  1. Start by identifying and describing each class in English. Note, this is following a top-down design where you first model all the objects in the enterprise and then you determine how they interact.
  2. Continue by drawing the UML class diagram by drawing the classes, but avoid filling in the attributes for now, just name the classes.
  3. Next, determine what relationships exist between the classes you identified. Draw each association in the diagram including the multiplicity constraints and describe in English (both directions) to make sure you've correctly modeled the information given.
  4. Now complete each class by filling in the attributes and their corresponding data type.
  5. Map the UML class diagram to the relational model by drawing the relation scheme diagram. Be sure to model all constraints such as any non-null attributes, primary key, and foreign key.

The solution to this exercise may be discussed in class by your instructor or posted online at a later date.