Oracle集合运算符
Oracle集合运算符:
集合运算符:UNION/UNION ALL 并集,INTERSECT 交集,MINUS 差集
- 一、union求并集,公共部分只有包含一次
- 例:求emp表ename中含’A‘或含有‘M’
- SQL> select * from emp where ename like '%A%'
- 2 union
- 3 select * from emp where ename like '%M%';
-
- 二、union all求集并,公共部分只有包含二次
- 例:求emp表ename中含’A‘或含有‘M’
- SQL> select * from emp where ename like '%A%'
- 2 union all
- 3 select * from emp where ename like '%M%';
-
- 三、intersect求交集,只有包含公共部分
- 例:求emp表ename中即含’A‘又含有‘M’
- SQL> select * from emp where ename like '%A%'
- intersect
- select * from emp where ename like '%M%';
-
- 四、minus求差集,求集合A去除集合A和集合B的交集
- 例:求emp表sal从700到1200
- SQL>select * from emp where sal between 700 and 1300
- minus
- select * from emp where sal between 1200 and 1400;
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