Placing this in its context of things said previously, "The DBMS doesn't read your mind before interpreting relations.", "Which is why the real interpretation happens outside the DBMS.", "Unfortunately, computer programs mean what they actually do", it is entirely irrelevant.
The meaning of what a DDL script does is that it asserts/ensures the (non-)existence of database objects in the database. This has absolutely nothing to do with the intended interpretation that the designer attaches to those of the database objects that are base tables/relations/relvars and derived ones in his design.
> The meaning of what a DDL script does is that it asserts/ensures the (non-)existence of database objects in the database.
The DDL also defines what database objects mean. It's the programmer's job to make sure database objects actually mean what the specification says they should mean. Calling it a “customer” isn't enough: it has to have the same attributes, as well as obey the same constraints, as a customer in your problem domain. If your DBMS can't enforce this, it's not a customer, no matter what you call it.
> This has absolutely nothing to do with the intended interpretation that the designer attaches to those of the database objects that are base tables/relations/relvars and derived ones in his design.
If your DBMS's DDL is sufficiently expressive, you can arrange things so that the behavior of your database objects matches your intended interpretation. (And, if it isn't sufficiently expressive, you should switch DBMSes.) This is the whole point to studying database models.
The meaning of what a DDL script does is that it asserts/ensures the (non-)existence of database objects in the database. This has absolutely nothing to do with the intended interpretation that the designer attaches to those of the database objects that are base tables/relations/relvars and derived ones in his design.