CREATE TABLE paperfield (fieldid INT, paperid INT)
CREATE TABLE paperdataset (paperid INT, datasetid INT)
CREATE TABLE paper (paperid INT, title VARCHAR, venueid INT, year INT, numciting INT, numcitedby INT, journalid INT)
CREATE TABLE writes (paperid INT, authorid INT)
CREATE TABLE journal (journalid INT, journalname VARCHAR)
CREATE TABLE cite (citingpaperid INT, citedpaperid INT)
CREATE TABLE paperkeyphrase (paperid INT, keyphraseid INT)
CREATE TABLE keyphrase (keyphraseid INT, keyphrasename VARCHAR)
CREATE TABLE author (authorid INT, authorname VARCHAR)
CREATE TABLE field (fieldid INT)
CREATE TABLE dataset (datasetid INT, datasetname VARCHAR)
CREATE TABLE venue (venueid INT, venuename VARCHAR)

How many papers were written on question answering in the past 5 years ?
SELECT DISTINCT COUNT(paper.paperid) FROM keyphrase, paper, paperkeyphrase WHERE keyphrase.keyphrasename = 'question answering' AND paperkeyphrase.keyphraseid = keyphrase.keyphraseid AND paper.paperid = paperkeyphrase.paperid AND paper.year >= YEAR(CURDATE()) - 5
SELECT DISTINCT COUNT("paper"."paperid") FROM "keyphrase" JOIN "paperkeyphrase" ON "keyphrase"."keyphraseid" = "paperkeyphrase"."keyphraseid" JOIN "paper" ON "paper"."paperid" = "paperkeyphrase"."paperid" AND "paper"."year" >= YEAR(CURDATE()) - 5 WHERE "keyphrase"."keyphrasename" = 'question answering'