You are writing a query and would like to know the total impressions that have been delivered per campaign, per supply_source, and per device_type. Which of the following represents how you should write the query?

Question

Accepted Answer

SELECT campaign, supply_source, device_type, SUM(impressions) AS impressions FROM dsp_impressions GROUP BY 1,2,3

Answer

SELECT total_impressions SUM(impressions) AS device_type FROM campaign, supply_source GROUP BY 1,2,3

Answer

SELECT campaign, supply_source, SUM(impressions) AS impressions FROM device_type GROUP BY 1,2