Database Reference
In-Depth Information
Figure 10.5. Diagramming a one-to-one relationship
The line that appears between the tables in the diagram indicates the type of relationship,
and there is a particular line that you use for each type. Later in this chapter, you'll learn
how to modify the line so that it also shows the characteristics of the relationship.
Figure
10.6
shows the relationship diagram for the EMPLOYEES and COMPENSATION tables
in
Figure 10.4
. (Note that a Data Table symbol represents each table.)
Figure 10.6. The relationship diagram for the EMPLOYEES and COMPENSATION
tables
One-to-Many Relationships
A
one-to-many
relationship exists between a pair of tables when a single record in the first
table can be related to one or more records in the second table, but a single record in the
second table can be related to
only one
record in the first table. Let's look at a generic ex-
ample of this type of relationship.
