Why would this query fail? SELECT campaign, SUM(impressions) AS impressions FROM dsp_impressions

The correct answer is There is no GROUP BY statement; this query cannot be run without aggregation on the campaign dimension because the query is attempting to perform an aggregation (SUM) on the impressions field while selecting the campaign field, but it does not include a GROUP BY clause to specify how the data should be grouped. In SQL, when using an aggregate function like SUM, all non-aggregated fields in the SELECT statement (such as campaign) must be included in a GROUP BY clause. Without this, the query cannot properly aggregate the impressions for each campaign, leading to a syntax error. The other options are not correct because a WHERE clause is not required for every query, and SELECT statements can indeed be used to choose metrics from a table.