多项选择题
A.inner join B.left join C.right join D.union
A.select*from t1 where city_name="北京"orcity_name="上海"; B.select*from t1 where city_name="北京"and city_name="上海"; C.select*from t1 where city_name in("北京","上海"); D.select*from t1 where city_name in"北京"or"上海";
A.客户行为的数据挖掘报告 B.描述性数据分析报告 C.产品和行为倾向报告 D.以上都不对