Database Reference
In-Depth Information
Figure 2.24
Database properties dialog.
Figure 2.25
Specify attributes.
6. To view the result, drag the
Database Properties
window to the bottom of the screen
and zoom the diagram to 100%.
Similarly, you can create other entities based on Figure 2.31.
Note: he above steps are performed on Windows 7 Professional with Microsoft Visio
2007 installed. You may use other database design software to obtain similar E-R diagrams.
Create relationships
: With Microsoft Visio, you can create relationships. he following
steps show how you can create relationships involved in the class registration data model:
1.
Creating identifying relationship
: Use the following steps to create an identifying
relationship connecting the entities BUILDING and CLASSROOM.
◾
Assume that you have created BUILDING and CLASSROOM entities as shown
in Figure 2.6. Click the
Connector Tool
icon on the tool bar. Move the mouse
cursor over the parent entity
BUILDING
. When a red rectangle appears, press
the mouse. hen, hold the mouse and move the cursor over to the child entity
CLASSROOM
. When a red rectangle appears around the CLASSROOM entity,
release the mouse. An identifying relationship connector is automatically drawn
from the parent entity to the child entity.
◾
To specify the cardinality, double click on the relationship connector line between
the entities BUILDING and CLASSROOM to open the Database Prosperities
dialog. Select
Miscellaneous
in the
Categories
pane. Check the option
One or
more
as shown in Figure 2.26.
he letter
P
should appear near the relationship connector line.
