COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Carriers WHERE CarrierName = 'Bob'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT CarrierId) AS DistinctValues FROM Carriers WHERE CarrierName = 'Bob'

AVG

Returns the average of the column values.

SELECT CarrierId, AVG(AnnualRevenue) FROM Carriers WHERE CarrierName = 'Bob'  GROUP BY CarrierId

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), CarrierId FROM Carriers WHERE CarrierName = 'Bob' GROUP BY CarrierId

MAX

Returns the maximum column value.

SELECT CarrierId, MAX(AnnualRevenue) FROM Carriers WHERE CarrierName = 'Bob' GROUP BY CarrierId

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM Carriers WHERE CarrierName = 'Bob'