StackOverflow response times by language, easy questions

response times by language.sql

select TagName, 
       avg(cast(ResponseTime as bigint)) as Average,
       stdev(cast(ResponseTime as bigint)) as StandardDev
from 
  (SELECT
         Questions.CreationDate, 
         Questions.Title, 
         Tags.TagName,
         Answers.CreationDate as ResponseDate,
         datediff(minute, Questions.CreationDate, 
                          Answers.CreationDate) as ResponseTime,
         cast(DATEPART(hour, Questions.CreationDate) as int) as ResponseHour
    FROM Posts Questions
    join Posts Answers on Answers.id = Questions.AcceptedAnswerId
                         and datediff(hour, Questions.CreationDate, Answers.CreationDate) < 5
    join PostTags ON PostTags.PostId = Questions.Id
    join Tags on Tags.Id = PostTags.TagId
    WHERE Questions.CreationDate > convert(datetime, '01/01/2012', 101)  
          and TagName in ('ruby', 'c++', 'c', 'clojure', 
                          'scala', 'javascript', 'haskell',
                          'c#', 'java', 'lua', 'php')
) as Responses
group by TagName
order by TagName