sql-server - 如何使此 SQL 查询工作(具有嵌套查询的计算列)？

Question

我想要一个计算列，如果字段 asofdate 等于表中的最大值 asofdate 则为真，否则为假。我尝试了以下但出现语法错误。执行此操作的正确方法是什么？

select 
case asofdate
when select max(asofdate) from sometable then 1
else 0
end 
from sometable

或者，是否可以按照以下行计算列

case asofdate
when END OF PREVIOUS MONTH then 1
else 0
end

Answer 1

来自MSDN article

A computed column is computed from an expression that can use other columns in the same table. The expression can be a noncomputed column name, constant, function, and any combination of these connected by one or more operators. The expression cannot be a subquery.

所以不，你不能那样做一个计算列。