SQL has a number of functions for counting, summing, averaging, and otherwise performing aggregate operations on a table. These functions enable us to perform a variety of queries. For example, we can count the number of members in the club or find the average handicap. We can group the data in different ways to find aggregates. For example, we might want to count the number of tournament entries in each individual year, or we might want to find the number of entries in each particular tournament.