Question

表格（来自http://www.tutorialspoint.com/sql/sql-using-joins.htm） 1）客户表：

 +----+----------+-----+-----------+----------+
| 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 |
+----+----------+-----+-----------+----------+

2）订单表：

+-----+---------------------+-------------+--------+
|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 |
+-----+---------------------+-------------+--------+

内连接查询是：

SELECT ID, NAME, AGE, AMOUNT
        FROM CUSTOMERS, ORDERS
        WHERE  CUSTOMERS.ID = ORDERS.CUSTOMER_ID;

显示的结果是：

+----+----------+-----+--------+
| ID | NAME     | AGE | AMOUNT |
+----+----------+-----+--------+
|  3 | kaushik  |  23 |   3000 |
|  3 | kaushik  |  23 |   1500 |
|  2 | Khilan   |  25 |   1560 |
|  4 | Chaitali |  25 |   2060 |
+----+----------+-----+--------+

我的问题：根据“ORDERS”表清楚地对结果表进行排序，即结果表中ID列中的结构为3,3,2,4 acc。到ORDERS表。为什么ID的排序不符合CUSTOMERS表，即为什么结果不是

和相应的值。那有什么规则吗？

Answer 1

您应该使用下面的订单

SELECT ID, NAME, AGE, AMOUNT
        FROM CUSTOMERS, ORDERS
        WHERE  CUSTOMERS.ID = ORDERS.CUSTOMER_ID order by ID asc;

Answer 2

在您定义查询结果之前，不会定义查询结果的顺序。如果您对特定订单感兴趣，请使用ORDER BY子句。

有人说......

不再使用旧式连接。每个RDBMS都支持SQL-92连接语法。
养成使用表名为列添加前缀的习惯。使用表别名来保存输入。

SELECT 
  c.ID, c.NAME, c.AGE, o.AMOUNT
FROM 
  CUSTOMERS c
  INNER JOIN ORDERS o ON c.ID = o.CUSTOMER_ID
ORDER BY
  c.ID;

如何确定记录顺序作为连接查询的结果

2 个答案: