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

how many papers does fahad pervaiz have ?
SELECT DISTINCT COUNT(DISTINCT writes.paperid) FROM author, writes WHERE author.authorname = 'fahad pervaiz' AND writes.authorid = author.authorid
SELECT DISTINCT COUNT(DISTINCT "writes"."paperid") FROM "author" JOIN "writes" ON "author"."authorid" = "writes"."authorid" WHERE "author"."authorname" = 'fahad pervaiz'