where 子句的执行顺序

看代码：

set statistics io on
set statistics time on
go
set statistics profile on
go

use pubs
select * from authors
where (au_fname like 's%' or au_fname like 'a%')
and (state like 'ca' or state like 'ut')
and (cast(zip as int) > 90000)

select * from authors
where (au_fname like 's%' or au_fname like 'a%')
and (cast(zip as int) > 90000)
and (state like 'ca' or state like 'ut')

select * from authors
where (cast(zip as int) > 90000)
and (au_fname like 's%' or au_fname like 'a%')
and (state like 'ca' or state like 'ut')

目的：想验证where语句的各个条件的查询顺序
环境：sqlserver 2005express版本
步骤：显示查询计划
结果：无一例外，都被统一成了这样的代码

|--clustered index scan(object:([pubs].[dbo].[authors].[upkcl_auidind]), where:(convert(int,[pubs].[dbo].[authors].[zip],0)>(90000) and ([pubs].[dbo].[authors].[au_fname] like 's%' or [pubs].[dbo].[authors].[au_fname] like 'a%') and ([pubs].[dbo].[authors].[state] like 'ca' or [pubs].[dbo].[authors].[state] like 'ut')))

结论：貌似在2005之前的版本中，where子句的顺序是从前往后的。但是又貌似在2005的版本中进行了优化，所有的顺序都被统一成了以过滤能力进行排序的语句。