-- Database schema
| Question : questiontext [ TEXT ] , questionid [ INTEGER ] primary_key | Survey : SurveyID [ INTEGER ] primary_key , Description [ TEXT ] | Answer : AnswerText [ TEXT ] , SurveyID [ INTEGER ] , UserID [ INTEGER ] , QuestionID [ INTEGER ] |
-- -- How many users, between the age 27 to 35, were surveyed in 2018?

SELECT T1.UserID FROM Answer AS T1 INNER JOIN Question AS T2 ON T1.QuestionID = T2.questionid WHERE T1.SurveyID = 2018 AND T2.questionid = 1 AND T1.AnswerText BETWEEN '27' AND '35';