视图是虚拟的表。封装了SELECT语句的层次，可用来简化数据处理，重新格式化或保护基础数据.
创建视图以便多次使用:

CREATE VIEW ViewName AS
SELECT ...
FROM ...

用视图格式化检索出的数据:

SELECT RTRIM(vend_name) + ' (' + RTRIM(vend_country) + ')'
    AS vend_title
FORM vendors
ORDER BY vend_name;