Application Relationship (AR)

An AR is similar to referential integrity in that references from one table to another are valid. However, the relationships are defined internally within the logic of application programs, rather than externally through Db2. Since application programs are not involved in an Edit session under File-AID for Db2, an external definition is required. You can meet this requirement by defining application relationships through File-AID for Db2’s Option 6, Relationships, or through Option 2, Edit. The relationship you define lets File-AID for Db2 simultaneously access tables with application relationships.

Application Relationship shows an application relationship. Every CUSTNO in the ORDER table must be a CUSTNO in the CUSTOMER table. Every ORDERNO in the PARTS table must be a ORDERNO in the ORDER table.

You define the relationship to relate columns from one table to another: The CUSTOMER table is a parent to the ORDER table. The ORDER table is a dependent to the CUSTOMER table, and a parent to the PARTS table. The PARTS table is a dependent to the ORDER table and a descendant to the CUSTOMER.

Application Relationship

Unlike referential integrity, an application relationship has no external control to enforce the specified relationships. Only the application program can prevent a user from entering a foreign key in a dependent table that does not exist in the parent table. However, once an AR is defined to File-AID for Db2 (see Creating-a-new-relationship), Related Table Edit can provide this control.