For all the users who have been asked "Have you ever been diagnosed with a mental health disorder?", how many of them said "Yes"?
have asked refers to questiontext; said 'Yes' refers to AnswerText = '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'
CREATE TABLE Question
(
    questiontext TEXT,
    questionid   INTEGER
        constraint Question_pk
            primary key
);
CREATE TABLE Survey
(
    SurveyID    INTEGER
        constraint Survey_pk
            primary key,
    Description TEXT
);
CREATE TABLE IF NOT EXISTS "Answer"
(
    AnswerText TEXT,
    SurveyID   INTEGER
        constraint Answer_Survey_SurveyID_fk
            references Survey,
    UserID     INTEGER,
    QuestionID INTEGER
        constraint Answer_Question_questionid_fk
            references Question,
    constraint Answer_pk
        primary key (UserID, QuestionID)
);
