Database Reference
In-Depth Information
Figure 10.29. Identifying the official relationship between the BUILDINGS and
CLASSES tables
Note that the relationship diagram is built from the perspective of the BUILDINGS table.
This is due to the fact that the BUILDINGS table is on the “one” side of the relationship.
When you create a simple diagram such as this, I recommend that you always show the
“one” side of the relationship on the left and the “many” side on the right. Following this
practice will make your diagrams easy to read and help ensure that you create them in a
consistent manner. (This practice is unnecessary, however, when you create a complex dia-
gram showing the relationships between several tables.)
Attheveryleast,youshouldincludeeachtable'sprimarykeyinthediagram.Doingsowill
prove to be a valuable visual aid when you begin to
establish
the relationships. You could
go so far as to display each table's complete structure (as you see in
Figure 10.30
), assum-
ing you have space on the diagram. Displaying the structures in this manner often helps to
reinforce the decision you've made regarding the type of relationship that exists between
the tables. (I use both types of diagrams throughout the remainder of the topic.)
