In the assignment type upload, you seem to be using the data1=notes and data2=submitted.

Since assignment type=upload is from AU assignment type, it would have been nice to maintain it in this format
data1=submitted and data2=notes

This way those that are already using AU assignment type do not have to do a lot of code change. Please can you reverse this now.

Or just add a new field in the submission table to hold the submission status.

Also, in the AU type, if there are more than one teacher and they all submit assignment responses, we keep note of which teacher submitted what. In the upload, this is not don't. Can you please fix this or add a field to hold the teacher user ids or change the teacher field value to varchar to hold the teacher userids.