Here's what I have so far but it's adding up ALL the tenants for each owner - not differentiating which owner. In other words, building 23 has had 5 tenants over the past 10 years and 3 owners. When I run the query below, it displays that each owner had 5 tenants.
SELECT o.ownerName, o.ownershipStarted, o.ownershipEnded, COUNT(t.tenantID)
FROM owner o
INNER JOIN tenant t ON o.buildingID = t.buildingID
AND o.buildingID = 23
GROUP BY o.ownerName