Adobe Campaign Business Practitioner (CBP) Certification Practice Exam

What is required for every column in a query when computing aggregates?

1. It must be a primary key

2. It must be aggregate or a group by

3. It must be a string data type

4. It must be distinct values only

The correct answer is: It must be aggregate or a group by

In the context of computing aggregates in SQL queries, having every column as either an aggregate function or included in a GROUP BY clause is essential. This requirement ensures that the database understands how to structure the results when summarizing data. When you use aggregate functions, like COUNT, SUM, AVG, MIN, or MAX, they need to operate on a dataset that's well-defined. If there are other columns in the SELECT statement that are not aggregated, those must be specified in the GROUP BY clause. This instruction allows the database to know how to group the results before applying the aggregation, thus creating coherent, meaningful summaries. This principle ensures that the resulting dataset from the query maintains a logical structure and avoids ambiguities in what values correspond to which aggregates. Without adhering to this rule, the database engine would likely throw an error or return unexpected results depending on its SQL mode. Other options do not meet the criteria necessary for ensuring accurate aggregate computations in SQL queries. For instance, a primary key being required does not apply since any column can be in the GROUP BY or aggregate function. String data types may be necessary for certain operations but are not a requirement for every column. Lastly, distinct values only are not mandatory; you can aggregate across all values, whether they