I get the following validation errors in SQL Server 2008, that you might add to the validator functions in Data Modeler.
Introducing FOREIGN KEY constraint 'Clients_Declarations' on table 'Declarations' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Cannot create the foreign key "Becons_Clients" with the SET NULL referential action, because one or more referencing columns are not nullable.
I know how to solve them, but it is just better if they are validated or automatically applied to the referenced fields (the second one could give a warning when choosing 'Set to null' in the constraint editor.
You are right, Data Modeler project validator should generate a warning for this type of relationship in SQL Server databases. We will include that.
TMS Software Team