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

Does hal perkins have any papers published ?
SELECT DISTINCT writes.paperid FROM author, writes WHERE author.authorname = 'hal perkins' AND writes.authorid = author.authorid
SELECT DISTINCT "writes"."paperid" FROM "author" JOIN "writes" ON "author"."authorid" = "writes"."authorid" WHERE "author"."authorname" = 'hal perkins'