sqlserver中All、Any和Some用法与区别

SQLServer中有三个关键字可以修改比较运算符：All、Any和Some，其中Some和Any等价。 

他们作用于比较运算符和子查询之间，作用类似Exists、not exists、in、not

in以及其他逻辑意义，这些语法同样被SQLServer2000支持但是很少看到有人用它们。

set nocount on  use tempdbgo  if (object_id ('t1') is not null)drop table t1create table t1 (n int)insert into t1 select 2 unionselect 3    if (object_id ('t2') is not null)drop table t2create table t2 (n int)insert into t2 select 1 unionselect 2 union select 3 union select 4  -- t1表数据 2,3-- t2表数据 1,2,3,4-- '>all' 表示:t2表中列n的数据大于t1表中列n的数据的数，结果只有4.select * from t2 where n > all(select n from t1 )    --4select * from t2 where n > any(select n from t1 )    --3,4select * from t2 where n > some(selectn from t1)      --3,4  select * from t2 where n = all(select n from t1 )    --无数据select * from t2 where n = any(select n from t1 )    --2,3select * from t2 where n = some(selectn from t1)      --2,3  select * from t2 where n < all(select n from t1 )    --1select * from t2 where n < any(select n from t1 )    --1,2select * from t2 where n < some(selectn from t1)      --1,2  select * from t2 where n <>all (select n from t1 )    --1,4select * from t2 where n <>any (select n from t1 )    --1,2,3,4select * from t2 where n <>some(select n from t1)      --1,2,3,4set nocount off

 

注意：1. =any 与in 等效.
2. 如果t1中包含null数据，那么所有All相关的比较运算将不会返回任何结果。因为t1和t2表的null的存在他们和notexists之类的比较符会有一些区别。
比如下面两句

select * from t2 a where not exists(select1 from t1 where n>=a.n) select * from t2 where  n > all(select n from t1) 

他们逻辑上意义很像但是对于null的处理却是恰恰相反，第一句会忽略子查询的null而把t2的null同时查出来，第二句却是忽略了t2的null同时会因为t1中的null而无法查询到数据。