��连接词in和not in用来判断一个元素是否在某个集合中。例如：
select distinct customer-name from borrower
where customer-name in (select customer-name from depositor)
和
select distinct customer-name from borrower
where customer-name not in ("Smith", "Jones")
因此集合成员资格确认的语法格式如下：
��(A1,A2,…,An) [in | not in] (Select-From-Where)
��