Confused about deleted Test Cases

Hi,

I've written some SQL that returns all Cases where the value of one custom field is "x" and the value of another field is "y" for a given project.

The results contain a number of Case IDs that cannot be found when searching via the TestRail UI. When I enter the C#, it says:

The specified test case was not found.

I'm assuming that these Cases have been deleted, but they still exist in the Cases table. Is there another table or field somewhere that prevents Cases from being searched or shown in the UI?

I just need to understand to a.) make sure nothing has gone wrong and b.) ensure these can be excluded from my results.

Thanks.