匿名通过本文主要向大家介绍了SQLServer,数据集合等相关知识,希望本文的分享对您有所帮助
SQLServer2005通过intersect,union,except和三个关键字对应交、并、差三种集合运算。
他们的对应关系可以参考下面图示相关测试实例如下：相关测试实例如下：
代码如下:
use tempdb
go
if (object_id ('t1' ) is not null ) drop table t1
if (object_id ('t2' ) is not null ) drop table t2
go
create table t1 (a int )
insert into t1 select 1 union select 2 union select 3
create table t2 (a int )
insert into t2 select 3 union select 4 union select 5
go
select * from t1 union select * from t2
go
/* 求表并集
1
2
3
4
5*/
select * from t1 union all select * from t2
go
/*求表并集不过滤重复
1
2
3
3
4
5*/
select * from t1 except select * from t2
go
/*求t1对t2的差集
1
2*/
select * from t1 intersect select * from t2
go
/*求t1对t2的交集
3*/