use tempdb

create table tempTable1 (id int primary key identity, price int)

create table tempTable2 (id int primary key identity, price int)

insert into tempTable1 select 3 union all select 1 union all select 2 union all select 3

insert into tempTable2 select 3 union all select 4 union all select 1 union all select 2

select * from temptable1

select * from temptable2

--union会删除重复值，也就是说A和B中重复的行，最终只会出现一次，而union all则会保留重复行。

select * from temptable1

union

select * from temptable2

select * from temptable1

union all

select * from temptable2

--差异（Except）

--就是两个集中不重复的部分。例如

SELECT * from temptable1

except

select * from temptable2

--交集（intersect)

--就是两个集*同的部分。例如

select * from temptable1

INTERSECT

select * from temptable2

DROP TABLE temptable1

DROP TABLE temptable2