Establishing Relationship Characteristics
Now you'll establish the characteristics of each relationship. These characteristics indicate what will occur when you delete a record, the type of participation each table bears within the relationship, and to what degree each table participates in the relationship.
Defining a Deletion Rule for Each Relationship
The first characteristic you'll establish for the relationship is a deletion rule. This rule determines what your RDBMS should do when you place a request to delete a given record in the parent table of the relationship. Deletion rules are crucial to relationship-level integrity because they help guard against orphaned records, which are records in the child table that have no relationship ...