Schema - user interface

The way the additional row of fields is created is kind of snazzy, but it's a bit contrary to normal drupal behavior. I would suggest adding an 'add another row' button of some sort, rather than auto-creating a new row when the field name field loses focus and has data present.

It's also not clear that you have to manually add the primary key field in the field list. This is probably an issue that can be fixed by adding a description to that field, or some help-text about how the form functions somewhere on the page.

It seems to work well though, user experience issues aside.