Which apps have not been updated since year 2015 and what kind of sentiment users hold on it?
since year 2015 refers to "Last Updated"<'January 1, 2015';
SELECT DISTINCT App, Sentiment FROM user_reviews WHERE App IN ( SELECT App FROM playstore WHERE CAST(SUBSTR('Last Updated', -4, 4) AS INTEGER) < 2015 )
CREATE TABLE IF NOT EXISTS "playstore"
(
    App              TEXT,
    Category         TEXT,
    Rating           REAL,
    Reviews          INTEGER,
    Size             TEXT,
    Installs         TEXT,
    Type             TEXT,
    Price            TEXT,
    "Content Rating" TEXT,
    Genres           TEXT
);
CREATE TABLE IF NOT EXISTS "user_reviews"
(
    App                    TEXT
        references "playstore" (App),
    Translated_Review      TEXT,
    Sentiment              TEXT,
    Sentiment_Polarity     TEXT,
    Sentiment_Subjectivity TEXT
);
