Database Reference
In-Depth Information
Note that the crow's foot symbol is always located next to the table on the “many” side of
the relationship.
Figure 10.11
shows the relationship diagram for the CUSTOMERS and
CUSTOMER RENTALS tables in
Figure 10.9
.
Figure 10.11. The relationship diagram for the CUSTOMERS and CUSTOMER
RENTALS tables
Many-to-Many Relationships
A pair of tables bears a
many-to-many
relationship when a single record in the first table
can be related to one or more records in the second table
and
a single record in the second
table can be related to one or more records in the first table.
Assume once again that you're working with TABLE A and TABLE B and that there is
a many-to-many relationship between them. Because of the relationship, a single record
in TABLE A can be related to one or more records (but not necessarily all) in TABLE B.
Conversely, a single record in TABLE B can be related to one or more records (but not
necessarily all) in TABLE A.
Figure 10.12
shows the relationship from the perspective of
each table.
