-- 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 ] |
-- -- For all the users who have been asked "Have you ever been diagnosed with a mental health disorder?", how many of them said "Yes"?

SELECT COUNT(T1.UserID) FROM Answer AS T1 INNER JOIN Question AS T2 ON T1.QuestionID = T2.questionid WHERE T2.questiontext LIKE 'Have you ever been diagnosed with a mental health disorder?' AND T1.AnswerText = 'Yes';