COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Employee WHERE EmployeeId = '1234'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT FirstName) AS DistinctValues FROM Employee WHERE EmployeeId = '1234'

AVG

Returns the average of the column values.

SELECT LastName, AVG(AnnualRevenue) FROM Employee WHERE EmployeeId = '1234'  GROUP BY LastName

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), LastName FROM Employee WHERE EmployeeId = '1234' GROUP BY LastName

MAX

Returns the maximum column value.

SELECT LastName, MAX(AnnualRevenue) FROM Employee WHERE EmployeeId = '1234' GROUP BY LastName

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM Employee WHERE EmployeeId = '1234'