SELECt在查询的投影（）阶段执行列别名和计算，该阶段在选择（
WHERe和
JOIN）阶段之后发生。因此，无法在
WHERe子句或
JOIN条件中引用它们，因为它们尚不存在。您可以将带有
SELECT子句的查询用作子查询，也可以在
WHERe子句中重复计算：
select *from(select [FirstName], difference([FirstName], 'mitch') as similarityfrom [Dev].[dbo].[Name]) srcwhere similarity > 2order by similarity desc
或者
select [FirstName], difference([FirstName], 'mitch') as similarityfrom [Dev].[dbo].[Name]where difference([FirstName], 'mitch') > 2order by similarity desc
