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 )
database name:db_id app_store
googleplaystore table googleplaystore Cols: App dtype text, Category dtype text, Rating dtype real, Reviews dtype integer, Size dtype text, Installs dtype text, Type dtype text, Price dtype text, Content Rating dtype text, Genres dtype text, 
googleplaystore_user_reviews table googleplaystore_user_reviews Cols: App dtype text, Translated_Review dtype text, Sentiment dtype text, Sentiment Polarity dtype text, Sentiment Subjectivity dtype text, 
