IANAL either, but how is a data model different from code? SQL is a
declarative language. Sure, it isn't Turing-complete without something
like PL/SQL. So the question is, if I look at some code (be it Tcl or
PL/SQL), and I get inspired, and I go write some other code that does
something very similar, am I creating a derivative work? I would bet
that there are plenty of lawyers out there who can answer "yes" to
that question.
Finally, your argument about SQL can apply to the other stuff you call
code: code is just the expression of a flow of ideas. SQL is code....
