Why would this query fail? SELECT campaign, SUM(impressions) AS impressions FROM dsp_impressions
- There is no GROUP BY statement; this query cannot be run without aggregation on the campaign dimension.
- There is no WHERE clause to filter the query results based on one or more conditions.
- SELECT statements can not be used to choose metrics from a table.
Explanation:
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.