COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Campaigns WHERE Id = '123'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT AccountId) AS DistinctValues FROM Campaigns WHERE Id = '123'

AVG

Returns the average of the column values.

SELECT Name, AVG(DailyBudget) FROM Campaigns WHERE Id = '123'  GROUP BY Name

MIN

Returns the minimum column value.

SELECT MIN(DailyBudget), Name FROM Campaigns WHERE Id = '123' GROUP BY Name

MAX

Returns the maximum column value.

SELECT Name, MAX(DailyBudget) FROM Campaigns WHERE Id = '123' GROUP BY Name

SUM

Returns the total sum of the column values.

SELECT SUM(DailyBudget) FROM Campaigns WHERE Id = '123'