COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Candidate WHERE CandidateName = 'Bob'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT Id) AS DistinctValues FROM Candidate WHERE CandidateName = 'Bob'

AVG

Returns the average of the column values.

SELECT CandidateName, AVG(AnnualRevenue) FROM Candidate WHERE CandidateName = 'Bob'  GROUP BY CandidateName

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), CandidateName FROM Candidate WHERE CandidateName = 'Bob' GROUP BY CandidateName

MAX

Returns the maximum column value.

SELECT CandidateName, MAX(AnnualRevenue) FROM Candidate WHERE CandidateName = 'Bob' GROUP BY CandidateName

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM Candidate WHERE CandidateName = 'Bob'