ความยาว ไม่จำเป็นต้องใช้ทุกตาราง
length.It is not neccessary to use all the tables.
 ReviewRejectionReasons:  Id [ number]  Name [ text]  Description [ text]  PostTypeId [ number] 
SELECT AVG(LENGTH(Body)) AS AverageLength, AVG(CAST(Score AS FLOAT) / ViewCount) AS QuestionScorePerViews, AVG(CAST(Score AS FLOAT) / ViewCount) + STDEV(CAST(Score AS FLOAT) / ViewCount) AS PlusOneSigma, AVG(CAST(Score AS FLOAT) / ViewCount) - STDEV(CAST(Score AS FLOAT) / ViewCount) AS MinusOneSigma FROM Posts WHERE PostTypeId = 1 AND LENGTH(Body) <= 8000 GROUP BY ROUND(LENGTH(Body), -2) ORDER BY ROUND(LENGTH(Body), -2)