Ok this is a MUST have, basically me and every professional I have come across loves the fact that we can first model our database clearly and logically in yEd (great product), but what would make it awesome would be the ability to then generate SQL create/alter statements from saved graphml files.
You can even make id or tablename_id names in to primary key or forgian keys.
and you can make it for different databases like mysql, sqlite, postgres and oracle.
An update of this feature would be to generate code for nosql databases such as mongodb, orientdb and couchdb.
Just think of it, you can document your db, create it, alter the document, save it as a new version and then instantly alter the actual db.