How to manage db structure evolution ?

[Jack First]

I'm not talking about version of the MySql database, but about my customers database structure version.

I need to set a label (version number) on their db to be able to follow the evolution. The next time my customer ask me for an upgrade of my soft, I will have to execute scripts to upgrade its database structure according to the evolution of my soft.

My questions are :

1. Is it possible to set a label (version number) on a MySql database structure ?
2. Is it possible to compare 2 MySql databases architecture in order to generate scripts to upgrade from one version to the next one ?

I'm still in testing different databases and those 2 points are the most important to be able to manage in the same time the evolutioin of the database structure and the soft.

Thanks a lot in advance.

Jack