“Show me your flowcharts and conceal your tables, and I shall continue to be mystified. Show me your tables, and I won't usually need your flowcharts; they'll be obvious.” - Fred Brooks
Yep, but if you think your database schema is "secret sauce", you're fooling yourself. You can almost always guess the database schema if you're given 10 minutes to play with the application.
Generally your schema is your code, which IS your IP - your data is often NOT your IP (and often might just be a list of facts, a thing which is not copyrightable)