What does an aggregate function do in a query?

An aggregate function is a crucial component in querying databases as it allows the computation of a single result from a group of values. This function performs operations such as summing values, calculating averages, or counting occurrences, transforming numerous individual values into a singular derived result. For example, if you have a dataset containing sales figures for various regions, using an aggregate function like SUM will give you the total sales for all regions combined, rather than displaying each individual figure.

The other options pertain to different aspects of database management or functionality. Establishing user permissions relates to the security protocols surrounding data access. Retrieving data from multiple tables involves using joins or other methods to integrate information, while increasing the size of the dataset implies adding more records or attributes rather than distilling data down to a single value. Hence, the distinct role of the aggregate function lies in its ability to summarize and condense data efficiently.