A SELECT statement can produce a list of rows that match a given set of conditions. This list provides the details about the selected rows. However, to know about the overall characteristics of the rows, a summary can be more valuable. Aggregate functions (also known as Summary functions) perform summary operations on a set of values, such as counting, averaging, or finding minimum or maximum values. They calculate a single value based on a group of values. However, the resulting value is based only on non NULL values from the selected rows (with the exception that COUNT(*) counts all rows). Functions such as AVG() that calculate summary values for groups are known as “aggregate” functions because they are based on aggregates or groups of values. There are several aggregate functions. Some of the most common are as follows; Aggregate Functions Definition MIN() Find the smallest value MAX()
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