Do the following exercises:

1. Consider the ERD given in Figure 3.21 (The AIRLINE database schema):
   1. Based on what you see in the diagram, explain the difference between flights, flight legs, and leg instances. Please give a short explanatory paragraph.
   2. The names of some of the attributes in this diagram are underlined with dotted lines. You’ll note that this notation is not explained in the Figure 3.14 cheatsheet. What does it mean?
   3. You’ll note that the “SEAT” entity has a total participation in the “RESERVATION” relationship (i.e., we would write the cardinality constraint {1,*} on the “LEG_INSTANCE” side of the relationship). Why do you think the database modelers did it this way?

   Store these answers in a single homework03_1.txt file.

2. Exercise 3.32 — Build/represent this ERD using tools of your own choosing and save in a single homework03_2.xyz file.

3. Exercise 9.11 — Implement the schema by hand for this exercise, based on the model from the previous question. No automatic schema generation is required. Store your implementation in homework03_3.sql.

4. Complete lab exercise 3.3.

You can turn in your models in any form (e.g., scanned hand-drawn models, powerpoint, etc.); the use of data-modeling tools is not required.

Checking in

We will grade your work according to the following criteria:

• 25% — Exercise 3.1
• 25% — Exercise 3.2
• 25% — Exercise 3.3
• 25% — Exercise 3.4