Lesson 1.5: Create a second subject area diagram

Create another subject area to connect entities to and from other entities.

Before you create a second subject area diagram, you must already have created a first subject area diagram. This is covered in Lesson 1.1: Create a subject area diagram.

1 In the Tutorial encyclopedia, right-click the diagram workspace and select Choices. Drag it onto the diagram workspace the entities Receptionist, Reservation, and Customer. Close the Select and Drag dialog box.

2 Create new entities Reception, Reservation_Form, Diary, Business Traveler, and Vacationer, referring to the diagram below for placement of the entities.

3 Select the Super-sub Relation line, and draw a line from Customer to Business Traveler, and another line from Customer to Vacationer.

Note As soon as you connect a super-sub relation line to the sub-entity, System Architect draws a dotted-line rectangular box around the entities. This line is a visual clue about the type of relationship. It expands automatically as sub-entities are added.

4 Select the Super-sub Relation line, and draw a line from Reception to Receptionist, and another line from Reception to Reservation_Form.

5 Select the Non-Identifying Relation line, and draw a line from Customer to Reservation. Name the line makes.

6 Select the Identifying Relation line, and draw a line from Reservation to Diary. Name the line maintains.

7 Select the Identifying Relation line, and draw a line from Diary to Reception. Name the line is used by.

8 Add the following attributes to the following entities (typing them into the attribute grid and pressing Enter after each one):

Entity	Add the Following Attributes
Diary	Diary_ID (and toggle on PK) RoomTypeAvailability
Reservation	Reservation_Number (and toggle on PK)
Business Traveler	Corporate_Discount
Vacationer	Vacation_Package_Discount
Receptionist	EmployeeID (and toggle on PK)

Note Foreign keys in a subject area diagram reflect the entity's position in the model diagram. You will notice that even though you have not propagated foreign keys for this subject model, the Reservation entity reflects the foreign keys from its relationship in the existing subject area model, Hotel Check-In

1 Select Dictionary > Update FKs. System Architect will examine the data model, and propagate foreign keys in child entities based on the relationship types between entities.