On which brand of phone are the most applications installed?
brand of phone refers to phone_brand; most applications are installed refers to MAX(COUNT(is_installed = 1));
SELECT T.phone_brand FROM ( SELECT T1.phone_brand, COUNT(T4.is_active) AS num FROM phone_brand_device_model2 AS T1 INNER JOIN gender_age AS T2 ON T1.device_id = T2.device_id INNER JOIN events_relevant AS T3 ON T2.device_id = T3.device_id INNER JOIN app_events_relevant AS T4 ON T3.event_id = T4.event_id WHERE T4.is_active = 1 GROUP BY T1.phone_brand ) AS T ORDER BY T.num DESC LIMIT 1