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

return me the number of the organizations in ' North America ' .
SELECT COUNT(DISTINCT (name)) FROM organization WHERE continent = 'North America'
SELECT COUNT(DISTINCT "name") FROM "organization" WHERE "continent" = 'North America'