>> Is there such a tool out there. I would like to generate such a diagram
>> starting from my sql statements I use to create my database.
>> They call it reverse enginering if I'm not mistaking.
Yes, there are tools available to do this. I'm not aware of any adequate
open source tools (scope for a new project here), but commercially there are
packages like ERWin, ERStudio, and others. If you perform a web search on
these two names, you will probably come up with others. Be warned, however,
they are not cheap.
MikeA