Wow - DDL and DML are an excellent idea. I'm getting really excited about learning how to use these new abstraction libraries. I have to say that I'm really blown away by some of the innovation and cutting edge technologies used by the Moodle development team. I've used ADODB for years but I'd never heard of XMLDB. I've just downloaded DBDesigner 4 so that I can start getting my head round XMLDB. Also, I've had a quick go at creating an install.xml file both manually and using the XMLDB editor. It works really nice - if all 3rd party developers stick to using the install.xml file then the cross-db compatibility of Moodle is going to be excellent. Well done dev team!