MySQL: Select rows, grouped by ID, where none of the rows have a value in a certain column
I was able to solve my problem with the following query:

SELECT SUM(CASE 
             WHEN o.CurrentOwner IS NULL THEN 1
             ELSE 0
           END) AS numNull,
       COUNT(*) AS total,
       LotID
         FROM owner o GROUP BY LotID HAVING numNull=total