Database Reference
In-Depth Information
Figure 3.17. The AGENTS and CLIENTS tables
Degree of Participation
The
degree of participation
determines the minimum number of records that a given table
must have associated with a single record in the related table and the maximum number of
records that a given table is allowed to have associated with a single record in the related
table.
Consider, once again, a relationship between two tables called TABLE_A and TABLE_B.
Youestablishthedegreeofparticipation forTABLE_Bbyindicatingaminimumandmax-
imum number of records in TABLE_B that can be related to a
single
record in TABLE_A.
If a single record in TABLE_A can be related to no less than one but no more than ten re-
cords in TABLE_B, then the degree of participation for TABLE_B is
1,10.
(The notation
for the degree of participation shows the minimum number on the left and the maximum
number on the right, separated by a comma.) You can establish the degree of participation
for TABLE_A in the same manner. You can identify the degree of participation for each
table in a relationship by determining the way the data in each table is related and how
you're using the data.
