From which city were more tweets posted, Bangkok or Chiang Mai?
"Bangkok" and "Chiang Mai" are both City
SELECT SUM(CASE WHEN T2.City = 'Bangkok' THEN 1 ELSE 0 END) AS bNum , SUM(CASE WHEN T2.City = 'Chiang Mai' THEN 1 ELSE 0 END) AS cNum FROM twitter AS T1 INNER JOIN location AS T2 ON T1.LocationID = T2.LocationID WHERE T2.City IN ('Bangkok', 'Chiang Mai')