select top 8000 identity(int,1,1) as N into nums from (select top 100 id=1 from sysobjects) as a, (select top 100 id=1 from sysobjects) as b, (select top 100 id=1 from sysobjects) as cselect * from (select top 100 id=1 from sysobjects) as a, (select top 100 id=1 from sysobjects) as b, (select top 100 id=1 from sysobjects) as c 是全联接 就是笛卡尔积 楼主可以比较 select top 8000 identity(int,1,1) as N from (select top 100 id=1 from sysobjects) as a, (select top 100 id=1 from sysobjects) as b, (select top 100 id=1 from sysobjects) as c 和 select top 8000 identity(int,1,1) as N from (select top 10 id=1 from sysobjects) as a, (select top 10 id=1 from sysobjects) as b, (select top 10 id=1 from sysobjects) as c 就应该明白了
(select top 100 id=1 from sysobjects) as a,
(select top 100 id=1 from sysobjects) as b,
(select top 100 id=1 from sysobjects) as cselect * from
(select top 100 id=1 from sysobjects) as a,
(select top 100 id=1 from sysobjects) as b,
(select top 100 id=1 from sysobjects) as c
是全联接
就是笛卡尔积
楼主可以比较
select top 8000 identity(int,1,1) as N from
(select top 100 id=1 from sysobjects) as a,
(select top 100 id=1 from sysobjects) as b,
(select top 100 id=1 from sysobjects) as c
和
select top 8000 identity(int,1,1) as N from
(select top 10 id=1 from sysobjects) as a,
(select top 10 id=1 from sysobjects) as b,
(select top 10 id=1 from sysobjects) as c
就应该明白了