When defining a foreign key relationship, what is required for the key table?

The requirement that the key table must be a transparent table is essential when defining a foreign key relationship in SAP. Transparent tables are database tables that have a one-to-one correspondence with the underlying database tables, meaning they can store data and are directly accessible for data operations. They also provide a structured format to enforce data integrity through relationships, such as foreign keys.

By enforcing referential integrity, a foreign key ensures that the relationships between tables remain consistent. In this context, a transparent table is designed to support these constraints effectively, as it is specifically tailored for storing business data and maintaining links to other tables.

Other table types, such as structures or internal tables, do not meet this criterion. Structures are used primarily for data definition and do not store data persistently in the database. Internal tables are in-memory tables used in program logic and cannot serve as the target of a foreign key relationship due to their non-permanence. Therefore, the requirement that the key table must be a transparent table ensures the proper implementation of foreign key relationships in the SAP environment.