Something like:

where;
due date <= to date() And ;
((a submitted date >= date() - 30 days And submitted date > due date) OR;
empty(submitted date))

>I have a table that lists documents that are due to our vendor. Each record has a Due Date and a Submitted Date field. My goal is to find out how many documents are late each month. My first attempt is to find all records that have a due date <= to date() And a submitted date >= date() - 30 days And submitted date > due date. This only gets some of the records. It misses the records that don't have a submitted date at all yet. How can these two criteria be combined together?