sql语句里的as用法

Question

select * from
(
select top 10 * from
--主Select
( select top 10 * from zhekousjia order by riqi desc ) as myt1
----主Select结束
order by riqi asc
) as myt2 order by riqi desc

后面的as myt1是什么意思？as是加在括号后面的吗？我在网上看一般都写在from的前面？哪位高手帮我解释一下，小弟不胜感激！谢谢！

Answer 1

看这个 SQL 你得从最里面看起( select top 10 * from zhekousjia order by riqi desc ) as myt1
第一次，myt1作为select top 10 * from zhekousjia order by riqi desc的结果集
再从这个结果集中按qiqi升序取得前十条，然后在按照日期降序取得 最后结果，同时， myt2同样是第二层的结果集