Question: What are the percentages of professional developers using the various programing languages?
SQL:
SELECT Languages.name, COUNT(Languages.id) * 100.0 / (SELECT COUNT(DISTINCT Responses.id) FROM Response_LanguageHaveWorkedWith JOIN Responses ON Responses.id = Response_LanguageHaveWorkedWith.Response_id WHERE Responses.ResponderDescription = 'I am a developer by profession') FROM Languages JOIN Response_LanguageHaveWorkedWith ON Languages.id = Response_LanguageHaveWorkedWith.Languages_id JOIN Responses ON Responses.id = Response_LanguageHaveWorkedWith.Response_id WHERE Responses.ResponderDescription = 'I am a developer by profession' GROUP BY Languages.name