SQL aggregate functions

The aggregate functions are shown in the following table:

Function	Parameters	Function
COUNT	([all| Distinct]expression)	Calculates the number of non-null values in an expression, which can be used for numeric columns, and to remove duplicate values when using Distice
COUNT	(*)	Calculates all rows, including null rows, and cannot use the DISTINCT keyword for count (*)
MIN	(expression)	Calculates the minimum value of an expression, which can be used for numeric, character, and date-time columns, but not for bit, text, image columns, and the MIN function ignores null values in an expression
MAX	(expression)	Calculates the maximum expression, which can be used for numeric, character, and date-time columns, but not for bit, text, image columns, and the MIN function ignores null values in an expression
SUM	([all| Distinct]expression)	Evaluates the and of all values of an expression, ignoring the null value in the expression, and deleting the duplicate value in the expression when using the DISTINCT keyword, which applies to the numeric column
Avg	([all| Distinct]expression)	Calculates the average of an expression that ignores null values and deletes duplicate values from the expression when using the DISTINCT keyword, and applies to numeric columns.