SAP DDIC DATABASE TABLES FORKEYREL

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ABAP_DDIC - Foreign Key Dependencies
A foreign key dependency is a semantic dependency between two DDIC database tables, namely a foreign key table and a check table.
The definition of a foreign key dependency is done in the foreign key table. By assigning check tables to table fields, the table fields become foreign keys.

Check table

Foreign Key
BEGIN_SECTION VERSION 5 OUT
Foreign key dependencies are evaluated during input checks, for input help on dynpros and in Web Dynpros, when creating views, and in lock objects. In the ABAP programming language or in AB_SQL , foreign keys are not evaluated.
In a check table, obsolete data can be flagged as obsolete. This has an effect on the input check and input help on dynpros or Web Dynpros.
END_SECTION VERSION 5 OUT