SQL INTERSECT子句/操作符用于合并两个SELECT语句，但只从第一个SELECT语句返回完全相同于第二个SELECT语句结果的所有行。这意味着INTERSECT是由两个SELECT语句返回相同的行(唯一)。
正如使用UNION操作，同样的规则可使用在INTERSECT运算符。 但MySQL不支持INTERSECT操作
语法
INTERSECT的基本语法如下：
SELECT column1 [, column2 ] FROM table1 [, table2 ] [WHERE condition] INTERSECT SELECT column1 [, column2 ] FROM table1 [, table2 ] [WHERE condition]
在这里，给定的条件可能是根据您的需要给定任意的表达。
例子：
考虑下面的两个表中，(a)CUSTOMERS表如下：
+----+----------+-----+-----------+----------+ | ID | NAME | AGE | ADDRESS | SALARY | +----+----------+-----+-----------+----------+ | 1 | Ramesh | 32 | Ahmedabad | 2000.00 | | 2 | Khilan | 25 | Delhi | 1500.00 | | 3 | kaushik | 23 | Kota | 2000.00 | | 4 | Chaitali | 25 | Mumbai | 6500.00 | | 5 | Hardik | 27 | Bhopal | 8500.00 | | 6 | Komal | 22 | MP | 4500.00 | | 7 | Muffy | 24 | Indore | 10000.00 | +----+----------+-----+-----------+----------+
(b)另一个ORDERS表如下：
+-----+---------------------+-------------+--------+ |OID | DATE | CUSTOMER_ID | AMOUNT | +-----+---------------------+-------------+--------+ | 102 | 2009-10-08 00:00:00 | 3 | 3000 | | 100 | 2009-10-08 00:00:00 | 3 | 1500 | | 101 | 2009-11-20 00:00:00 | 2 | 1560 | | 103 | 2008-05-20 00:00:00 | 4 | 2060 | +-----+---------------------+-------------+--------+
现在，让我们在SELECT语句中加入这两个表如下：
SQL> SELECT ID, NAME, AMOUNT, DATE
FROM CUSTOMERS
LEFT JOIN ORDERS
ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID
INTERSECT
SELECT ID, NAME, AMOUNT, DATE
FROM CUSTOMERS
RIGHT JOIN ORDERS
ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID;
这将产生以下结果：
+------+---------+--------+---------------------+ | ID | NAME | AMOUNT | DATE | +------+---------+--------+---------------------+ | 3 | kaushik | 3000 | 2009-10-08 00:00:00 | | 3 | kaushik | 1500 | 2009-10-08 00:00:00 | | 2 | Ramesh | 1560 | 2009-11-20 00:00:00 | | 4 | kaushik | 2060 | 2008-05-20 00:00:00 | +------+---------+--------+---------------------+
