COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Person WHERE City = 'Miami'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT unid) AS DistinctValues FROM Person WHERE City = 'Miami'

AVG

Returns the average of the column values.

SELECT FirstName, AVG(AnnualRevenue) FROM Person WHERE City = 'Miami'  GROUP BY FirstName

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), FirstName FROM Person WHERE City = 'Miami' GROUP BY FirstName

MAX

Returns the maximum column value.

SELECT FirstName, MAX(AnnualRevenue) FROM Person WHERE City = 'Miami' GROUP BY FirstName

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM Person WHERE City = 'Miami'