COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Pages WHERE Id = '10000'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT Key) AS DistinctValues FROM Pages WHERE Id = '10000'

AVG

Returns the average of the column values.

SELECT Name, AVG(Size) FROM Pages WHERE Id = '10000'  GROUP BY Name

MIN

Returns the minimum column value.

SELECT MIN(Size), Name FROM Pages WHERE Id = '10000' GROUP BY Name

MAX

Returns the maximum column value.

SELECT Name, MAX(Size) FROM Pages WHERE Id = '10000' GROUP BY Name

SUM

Returns the total sum of the column values.

SELECT SUM(Size) FROM Pages WHERE Id = '10000'