SQL 中的 INTERSECT Clause函数

SQL INTERSECT 子句用于组合两个SELECT语句，但仅返回第一个SELECT语句中与第二个SELECT语句中的行相同的行。这意味着INTERSECT仅返回两个SELECT语句返回的公共行，MySQL不支持INTERSECT运算符。

INTERSECT - 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]

INTERSECT - 示例

请考虑以下两个表。

表1 -客户表(CUSTOMERS)如下

无涯教程网

+----+----------+-----+-----------+----------+
| 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 | Learnfk    |  24 | Indore    | 10000.00 |
+----+----------+-----+-----------+----------+

表2 -订单表(ORDERS)如下。

+-----+---------------------+-------------+--------+
|OID  | DATE                | CUSTOMER_ID | AMOUNT |
+-----+---------------------+-------------+--------+
| 102 | 2019-10-08 00:00:00 |           3 |   3000 |
| 100 | 2019-10-08 00:00:00 |           3 |   1500 |
| 101 | 2019-11-20 00:00:00 |           2 |   1560 |
| 103 | 2018-05-20 00:00:00 |           4 |   2060 |
+-----+---------------------+-------------+--------+

现在，让无涯教程按如下所示将这两个表连接到SELECT语句中。

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;

这将产生以下输出。

+------+---------+--------+---------------------+
| ID   | NAME    | AMOUNT | DATE                |
+------+---------+--------+---------------------+
|    3 | kaushik |   3000 | 2019-10-08 00:00:00 |
|    3 | kaushik |   1500 | 2019-10-08 00:00:00 |
|    2 | Ramesh  |   1560 | 2019-11-20 00:00:00 |
|    4 | kaushik |   2060 | 2018-05-20 00:00:00 |
+------+---------+--------+---------------------+