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

datasets in knn papers
SELECT DISTINCT dataset.datasetid FROM dataset, keyphrase, paperdataset, paperkeyphrase WHERE keyphrase.keyphrasename = 'knn' AND paperdataset.datasetid = dataset.datasetid AND paperkeyphrase.keyphraseid = keyphrase.keyphraseid AND paperkeyphrase.paperid = paperdataset.paperid
SELECT DISTINCT "dataset"."datasetid" FROM "dataset" JOIN "paperdataset" ON "dataset"."datasetid" = "paperdataset"."datasetid" JOIN "paperkeyphrase" ON "paperdataset"."paperid" = "paperkeyphrase"."paperid" JOIN "keyphrase" ON "keyphrase"."keyphraseid" = "paperkeyphrase"."keyphraseid" AND "keyphrase"."keyphrasename" = 'knn'