COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM ProductCategory WHERE CategoryOwner = 'Bob'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT CategoryId) AS DistinctValues FROM ProductCategory WHERE CategoryOwner = 'Bob'

AVG

Returns the average of the column values.

SELECT CategoryName, AVG(AnnualRevenue) FROM ProductCategory WHERE CategoryOwner = 'Bob'  GROUP BY CategoryName

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), CategoryName FROM ProductCategory WHERE CategoryOwner = 'Bob' GROUP BY CategoryName

MAX

Returns the maximum column value.

SELECT CategoryName, MAX(AnnualRevenue) FROM ProductCategory WHERE CategoryOwner = 'Bob' GROUP BY CategoryName

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM ProductCategory WHERE CategoryOwner = 'Bob'