CREATE TABLE domain_journal (did NUMBER, jid NUMBER)
CREATE TABLE publication (abstract VARCHAR2, cid NUMBER, citation_num NUMBER, jid NUMBER, pid NUMBER, reference_num NUMBER, title VARCHAR2, year NUMBER)
CREATE TABLE domain (did NUMBER, name VARCHAR2)
CREATE TABLE author (aid NUMBER, homepage VARCHAR2, name VARCHAR2, oid NUMBER)
CREATE TABLE publication_keyword (kid NUMBER, pid NUMBER)
CREATE TABLE conference (cid NUMBER, homepage VARCHAR2, name VARCHAR2)
CREATE TABLE cite (cited NUMBER, citing NUMBER)
CREATE TABLE keyword (keyword VARCHAR2, kid NUMBER)
CREATE TABLE journal (homepage VARCHAR2, jid NUMBER, name VARCHAR2)
CREATE TABLE domain_conference (cid NUMBER, did NUMBER)
CREATE TABLE organization (continent VARCHAR2, homepage VARCHAR2, name VARCHAR2, oid NUMBER)
CREATE TABLE writes (aid NUMBER, pid NUMBER)
CREATE TABLE domain_keyword (did NUMBER, kid NUMBER)
CREATE TABLE domain_author (aid NUMBER, did NUMBER)
CREATE TABLE domain_publication (did NUMBER, pid NUMBER)

return me the number of the keywords of ' Making database systems usable ' .
SELECT COUNT(DISTINCT (keyword.keyword)) FROM keyword, publication, publication_keyword WHERE publication_keyword.kid = keyword.kid AND publication.pid = publication_keyword.pid AND publication.title = 'Making database systems usable'
SELECT COUNT(DISTINCT "keyword"."keyword") FROM "keyword" JOIN "publication_keyword" ON "keyword"."kid" = "publication_keyword"."kid" JOIN "publication" ON "publication"."pid" = "publication_keyword"."pid" AND "publication"."title" = 'Making database systems usable'