Function Type	Name	Description	Ignores Nulls	Datatypes Supported
	General	AVG(expr)	Returns the mean of all values in the expression.	Yes	Numeric
		MAX(expr)	Returns the greatest value in the expression.	Yes	Numeric, character, datetime
		MIN(expr)	Returns the smallest value in the expression.	Yes	Numeric, character, datetime
		SUM(expr)	Returns the total of all the values in the expression.	Yes	Numeric
		COUNT(expr)	Returns the number of non-null values in the expression.	Yes	Numeric, character
		COUNT(*)	Returns the number of records. This function takes no expression.	No	N/A
	Statistical	STDEV(expr)	Returns the standard deviation of all expression values.	Yes	Numeric
		STDEVP(expr)	Returns the standard deviation for the population of all expression values.	Yes	Numeric
		VAR(expr)	Returns the variance of all expression values.	Yes	Numeric
		VARP(expr)	Returns the variance for the population of all	Yes	Numeric expression values.

Table 1 What's Your Function? The aggregate functions each support different datatypes and handle null column values differently. The functions are simple and not especially powerful in and of themselves, but you can combine them to create robust, powerful, complex queries.