SQL Server all（select ...）为null

Question

我搜索但我找不到任何关于它的信息。我需要SQL服务器查询，如

select t1.x 
 from @tablename as t1 
 where all
   (select t2.y from @tablename as t2 where t1.x=t2.x) is null

@tablename是相同的

但我无法使用all(select ...) is null部分查询。

感谢。

Answer 1

您想要update TableName set enddate = dateadd(day,1,startdate) 吗？

not exists

这测试没有匹配的值。

或者，或许，

select t1.x 
from @tablename as t1 
where not exists (select t2.y from @tablename as t2 where t1.x = t2.x) 

这会测试select t1.x from @tablename t1 where not exists (select 1 from @tablename as t2 where t1.x = t2.x and t2.y is not null ) ; 的所有匹配值都为NULL。