【发布时间】:2018-07-07 23:24:40
【问题描述】:
如果我在视图中选择某些列,内部 SQL Server 将首先选择表/表的所有列,然后进行子查询?
例如:
名为 THEVIEW 的视图可能是:
Select id, LTrim(RTrim(Name)) as Name, Age, Age-1 as AgeMinus1
From Persons
然后我会查询视图:
Select id, AgeMinus1
From THEVIEW
内部查询是这样的:
Select id, Age-1 as AgeMinus1
From Persons
或者这个(然后只显示 id,AgeMinus1:
Select id, LTrim(RTrim(Name)) as Name, Age, Age-1 as AgeMinus1
From Persons
谢谢大家!!!
【问题讨论】:
标签: sql-server performance views