Oracle 做並集-union、差集minus、交集intersect

創建測試數據：

create table A(ID NUMBER,NAME VARCHAR2(10));
insert into A
	select 1 as ID,'北京' as NAME from dual union all
	select 2 as ID,'上海' as NAME from dual union all
	select 3 as ID,'廣州' as NAME from dual;


create table B(ID NUMBER,NAME VARCHAR2(10));
insert into B
	select 1 as ID,'北京' as NAME from dual union all
	select 2 as ID,'上海' as NAME from dual union all
	select 4 as ID,'深圳' as NAME from dual;

commit;

A表與B表 

並集：

union（對合成的結果去重）

select * from A 
union 
select * from B;

 

union all（完全合成兩個表）

select * from A 
union all
select * from B;

交集：intersect（取在A表與B表同時存在的數據） 

select * from A 
intersect
select * from B;

差集：minus（取在A表中存在但是B表中不存在的數據）

select * from A 
minus
select * from B;

注意，這裏的函數都需要兩個表有相同的表結構。

有個小技巧，可以查詢Oracle數據庫的指定行到指定行的數據：

select * from A where ROWNUM <=3
minus
select * from A where ROWNUM <=2;