Among all the devices with event no.2 happening, what is the percentage of the device being a vivo phone?
event no. refers to event_id; event_id = '2'; percentage = SUM(IF(phone_brand = 'vivo',1,0)), COUNT(device_id) WHERE event_id = '2'; vivo phone refers to phone_brand = 'vivo';
SELECT SUM(IIF(T2.phone_brand = 'vivo', 1, 0)) / COUNT(T1.device_id) AS per FROM events AS T1 INNER JOIN phone_brand_device_model2 AS T2 ON T1.event_id = T2.device_id WHERE T1.event_id = '2'