Define Aggregate functions and what aggregate functions supported by the MySQL
To calculate a summary value from a set of individual values and uses one of the functions known as aggregate functions.
These are so called for the reason that they operate on aggregates (groups) of values.
Aggregate functions include COUNT ( ) which counts records or values in a query result; MAX( ) and MIN( ) which find largest and smallest values; SUM( ) and AVG( )and which produce sums and means of values.