What is the average result of the question "What is your age?" in 2014's survey?
average result refers to avg(AnswerText(SurveyID = 2014& QuestionID = 1))
SELECT CAST(SUM(T2.AnswerText) AS REAL) / COUNT(T2.UserID) AS "avg" FROM Question AS T1 INNER JOIN Answer AS T2 ON T1.questionid = T2.QuestionID WHERE T2.SurveyID = 2014 AND T1.questiontext LIKE 'What is your age?'
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)
);
