COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Activities WHERE FullName = 'Anna'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT FullName) AS DistinctValues FROM Activities WHERE FullName = 'Anna'

AVG

Returns the average of the column values.

SELECT Company, AVG(AnnualRevenue) FROM Activities WHERE FullName = 'Anna'  GROUP BY Company

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), Company FROM Activities WHERE FullName = 'Anna' GROUP BY Company

MAX

Returns the maximum column value.

SELECT Company, MAX(AnnualRevenue) FROM Activities WHERE FullName = 'Anna' GROUP BY Company

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM Activities WHERE FullName = 'Anna'