让我们先来看看在Oracle中如何使用INTERSECT和MINUS：

Oracle的集合操作包括: union , intersect , minus.

[例子]

假设有两个表a,b如下:

SQL> select * from a;

      COLA
———-
1
2
3

SQL> select * from b;

      COLB
———-
3
4
5

union : 得到两个结果集的并集(不含重复值)

SQL> select * from a
2 union
3 select * from b;

      COLA
———-
1
2
3
4
5

union all : 得到两个结果集的并集(所有值,包括重复值)

SQL> select * from a
2 union all
3 select * from b;

      COLA
———-
1
2
3
3
4
5

minus : 求前一个结果集减去后一个结果集的差集.

SQL> select * from a
2 minus
3 select * from b;

      COLA
———-
1
2

intersect : 求两个结果集的交集.

SQL> select * from a
2 intersect
3 select * from b;

      COLA
———-
3

[注意] 结果集中的对应列之间的数据类型必须相同才能进行合并,否则会出现异常.

这里Oracle使用并集、差集、交集起来很是轻尔易取，但是我们也想在MYSQL中使用并、交、差集合，应该怎样做呢？

mysql中intersect替代方法

MySQL中如何实现以下SQL查询
(SELECT S.Name
FROM STUDENT S, TRANSCRIPT T
WHERE S.StudId = T.StudId AND T.CrsCode = ‘CS305′)
INTERSECT
(SELECT S.Name
FROM STUDENT S, TRANSCRIPT T
WHERE S.StudId = T.StudId AND T.CrsCode = ‘CS315′)

select a.* from
(
SELECT S.Name
FROM STUDENT S, TRANSCRIPT T
WHERE S.StudId = T.StudId AND T.CrsCode = ‘CS305‘
) as a
cross join
(
SELECT S.Name
FROM STUDENT S, TRANSCRIPT T
WHERE S.StudId = T.StudId AND T.CrsCode = ‘CS315‘
) as b on a.Name = b.Name;

MySQL不支持INTERSECT和MINUS，及其替代方法

Doing INTERSECT and MINUS in MySQL

By Carsten | October 3, 2005

Doing an INTERSECT

An INTERSECT is simply an inner join where we compare the tuples of one table with those of the other, and select those that appear in both while weeding out duplicates. So

SELECT member_id, name FROM a
INTERSECT
SELECT member_id, name FROM b

can simply be rewritten to

SELECT a.member_id, a.name
FROM a INNER JOIN b
USING (member_id, name)

Performing a MINUS
To transform the statement

SELECT member_id, name FROM a
MINUS
SELECT member_id, name FROM b

into something that MySQL can process, we can utilize subqueries (available from MySQL 4.1 onward). The easy-to-understand transformation is:

SELECT DISTINCT member_id, name
FROM a
WHERE (member_id, name) NOT IN
(SELECT member_id, name FROM table2);


Of course, to any long-time MySQL user, this is immediately obvious as the classical use-left-join-to-find-what-isn’t-in-the-other-table:

SELECT DISTINCT a.member_id, a.name
FROM a LEFT JOIN b USING (member_id, name)
WHERE b.member_id IS NULL