What is one potential restriction for database views in ABAP?

Database views in ABAP are defined in such a way that they can represent data from multiple tables, often requiring a structured relationship between those tables. Specifically, when creating a view, utilizing tables that have foreign key relationships helps ensure data integrity and meaningful joins. This requirement allows the view to properly link data across related tables, thereby enhancing the accuracy and relevance of the data that is represented.

When tables are joined without these foreign key relationships, it can lead to ambiguous and unintended results, compromising the utility of the view. Therefore, having tables with foreign key relationships is a fundamental requirement that allows for the effective formation of views in ABAP, enabling consistent and reliable access to related data.

In contrast, the other options do not align with the principles governing database views in ABAP, either by suggesting restrictions that are not present or by promoting configurations that could lead to inconsistencies in the data structure.