MySQL: Select rows, grouped by ID, where none of the rows have a value in a certain column Confusing title, I know. Ii couldn't think of a better way to word it.
Basically, I have a table like this:

OwnerID | LotID | CurrentOwner

The OwnerID is the unique key for the table. This value is never repeated.
The LotID IS repeated. This table stores historical owner records for lots.
The CurrentOwner column simply contains a Y or NULL for each row. It is possible for one LotID to have multiple owners.

What I need is basically just for reporting. I need to know which LotIDs DO NOT have a "Y" for CurrentOwner in any of their rows. If I had the following data:

1, 1, Y  
2, 1, NULL  
3, 1, NULL  
4, 2, NULL  
5, 2, NULL  
6, 3, Y  
7, 3, NULL


Then I would need to know that LotID #2 does not have any owners currently.
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