COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Customers WHERE LastName = 'Cook'

COUNT(DISTINCT)

Returns the number of distinct, non-null field values matching the query criteria.

SELECT COUNT(DISTINCT ListId) AS DistinctValues FROM Customers WHERE LastName = 'Cook'

AVG

Returns the average of the column values.

SELECT LastName, AVG(AnnualRevenue) FROM Customers WHERE LastName = 'Cook'  GROUP BY LastName

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), LastName FROM Customers WHERE LastName = 'Cook' GROUP BY LastName

MAX

Returns the maximum column value.

SELECT LastName, MAX(AnnualRevenue) FROM Customers WHERE LastName = 'Cook' GROUP BY LastName

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM Customers WHERE LastName = 'Cook'