COUNT

Returns the number of rows matching the query criteria.

SELECT COUNT(*) FROM Tweets WHERE From_User_Name = 'twitter'

COUNT(DISTINCT)

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

SELECT COUNT(DISTINCT From_User_Name) AS DistinctValues FROM Tweets WHERE From_User_Name = 'twitter'

AVG

Returns the average of the column values.

SELECT Text, AVG(AnnualRevenue) FROM Tweets WHERE From_User_Name = 'twitter'  GROUP BY Text

MIN

Returns the minimum column value.

SELECT MIN(AnnualRevenue), Text FROM Tweets WHERE From_User_Name = 'twitter' GROUP BY Text

MAX

Returns the maximum column value.

SELECT Text, MAX(AnnualRevenue) FROM Tweets WHERE From_User_Name = 'twitter' GROUP BY Text

SUM

Returns the total sum of the column values.

SELECT SUM(AnnualRevenue) FROM Tweets WHERE From_User_Name = 'twitter'