COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Projects WHERE Id = 'MyId'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT Id) AS DistinctValues FROM Projects WHERE Id = 'MyId'

AVG

Returns the average of the column values.

SELECT Name, AVG(DocumentsCount) FROM Projects WHERE Id = 'MyId'  GROUP BY Name

MIN

Returns the minimum column value.

SELECT MIN(DocumentsCount), Name FROM Projects WHERE Id = 'MyId' GROUP BY Name

MAX

Returns the maximum column value.

SELECT Name, MAX(DocumentsCount) FROM Projects WHERE Id = 'MyId' GROUP BY Name

SUM

Returns the total sum of the column values.

SELECT SUM(DocumentsCount) FROM Projects WHERE Id = 'MyId'