Hi Susan, my name is Greg, but thanks! I'm glad you've gotten some value out of my work. 
As far as copyrighting is concerned, it's a tricky animal and I'm not an expert but here's my understanding:
Like you say for music, you can't copyright individual words or notes or chords. What you can do is copyright the work as a whole or significant and distinct portions of it.
As far as your collegue's design goes, the design is certainly copyrighted. Either he owns his design or the company he works for does. That means that you can't legally duplicate the entire database for yourself without permission, nor can you copy a signifcant portion - like the table structures - and then build the rest yourself.
What you certainly can do is take the concept and then build your own version from scratch. You know what you want the database to do, and you have a rough idea of how to do it. You're free to design your own version and, as long as it has significant differences unique to your version, you should have no worries about copyright infringement.

As far as copyrighting is concerned, it's a tricky animal and I'm not an expert but here's my understanding:
Like you say for music, you can't copyright individual words or notes or chords. What you can do is copyright the work as a whole or significant and distinct portions of it.
As far as your collegue's design goes, the design is certainly copyrighted. Either he owns his design or the company he works for does. That means that you can't legally duplicate the entire database for yourself without permission, nor can you copy a signifcant portion - like the table structures - and then build the rest yourself.
What you certainly can do is take the concept and then build your own version from scratch. You know what you want the database to do, and you have a rough idea of how to do it. You're free to design your own version and, as long as it has significant differences unique to your version, you should have no worries about copyright infringement.