Provide the number of airplanes that landed on Oakland Airport on 2018/8/7.
landed on refers to DEST; Oakland Airport refers to Description which contains 'Oakland'; on 2018/8/7 refers to FL_DATE = '2018/8/7';
SELECT SUM(CASE WHEN T1.Description LIKE '%Oakland%' THEN 1 ELSE 0 END) AS count FROM Airports AS T1 INNER JOIN Airlines AS T2 ON T1.Code = T2.DEST WHERE T2.FL_DATE = '2018/8/7'