Database schema:

CREATE TABLE playstore (
	"App" TEXT -- example: ['Photo Editor & Candy Camera & Grid & ScrapBook', 'Coloring book moana'],
	"Category" TEXT -- example: ['AUTO_AND_VEHICLES', 'ART_AND_DESIGN'],
	"Rating" REAL -- example: ['3.9', '4.1'],
	"Reviews" INTEGER -- example: ['159', '967'],
	"Size" TEXT -- example: ['19M', '14M'],
	"Installs" TEXT -- example: ['500,000+', '10,000+'],
	"Type" TEXT -- example: ['Paid', 'Free'],
	"Price" TEXT -- example: ['0', '$4.99'],
	"Content Rating" TEXT -- example: ['Everyone', 'Teen'],
	"Genres" TEXT -- example: ['Art & Design;Pretend Play', 'Art & Design']
)


CREATE TABLE user_reviews (
	"App" TEXT -- example: ['104 找工作 - 找工作 找打工 找兼職 履歷健檢 履歷診療室', '10 Best Foods for You'],
	"Translated_Review" TEXT -- example: ["I like eat delicious food. That's I'm cooking food", 'This help eating healthy exercise regular basis'],
	"Sentiment" TEXT -- example: ['nan', 'Positive'],
	"Sentiment_Polarity" TEXT -- example: ['1.0', '0.25'],
	"Sentiment_Subjectivity" TEXT -- example: ['0.5333333333333333', '0.28846153846153844'],
	CONSTRAINT fk_user_reviews_playstore FOREIGN KEY("App") REFERENCES playstore ("App")
)

Question: Which apps have not been updated since year 2015 and what kind of sentiment users hold on it?
Evidence: since year 2015 refers to "Last Updated"<'January 1, 2015';

SQL:
SELECT DISTINCT App, Sentiment FROM user_reviews WHERE App IN ( SELECT App FROM playstore WHERE CAST(SUBSTR('Last Updated', -4, 4) AS INTEGER) < 2015 )