COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM User WHERE CN = 'Administrator'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT Id) AS DistinctValues FROM User WHERE CN = 'Administrator'

AVG

Returns the average of the column values.

SELECT CN, AVG(AnnualRevenue) FROM User WHERE CN = 'Administrator'  GROUP BY CN

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), CN FROM User WHERE CN = 'Administrator' GROUP BY CN

MAX

Returns the maximum column value.

SELECT CN, MAX(AnnualRevenue) FROM User WHERE CN = 'Administrator' GROUP BY CN

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM User WHERE CN = 'Administrator'