캐글 advanced_sql/04-writing-efficient-queries

WITH LocationsAndOwners AS 
(
SELECT * 
FROM CostumeOwners co INNER JOIN CostumeLocations cl
   ON co.CostumeID = cl.CostumeID
),
LastSeen AS
(
SELECT CostumeID, MAX(Timestamp)
FROM LocationsAndOwners
GROUP BY CostumeID
)
SELECT lo.CostumeID, Location 
FROM LocationsAndOwners lo INNER JOIN LastSeen ls 
    ON lo.Timestamp = ls.Timestamp AND lo.CostumeID = ls.CostumeID
WHERE OwnerID = MitzieOwnerID