An Aggregate function in SQL performs a calculation on a set of values and returns a single value as the result. Common aggregate functions include:
COUNT(): Returns the count of rows (number of rows) present in the result set.
SUM(): Calculates the sum of a numeric column in a result set.
AVG(): Calculates the average of a numeric column in a result set.
MAX(): Returns the highest value (maximum) of a column present in the result set.
MIN(): Returns the lowest value (minimum) of a column present in the result set