在 phpmyadmin 和 SQL Fiddle 上执行时相同 SELECT 查询的不同结果

Posted 2023-02-25

【中文标题】在 phpmyadmin 和 SQL Fiddle 上执行时相同 SELECT 查询的不同结果

【英文标题】：Different Results for Same SELECT Query When Executing on phpmyadmin and SQL Fiddle

【发布时间】：2015-09-15 09:15:22

【问题描述】：

我编写了一个查询以获取 MySQL 中所有 国家 的最新 tax强>表。在 phpmyadmin(localhost) 和 SQL Fiddle 中执行相同的查询。两种结果是不同的。但是 SQL Fiddle 会产生正确的结果。

我可以找到相同的问题 发表在 Stack Overflow 之前的 Link

我没有从帖子中得到任何帮助。我的问题是如何在 phpmyadmin(localhost) 上为我在下面写的 SELECT 查询获得正确的结果；我的SELECT 查询有问题吗？

选择查询：（我在 Phpmyadmin 和 SQL Fiddle 上都执行过）

SELECT 
  t1.id, t1.country, 
  t1.tax, t1.created_by, 
  t1.created_on, t1.modified_by, t1.modified_on 
FROM tax t1 
INNER JOIN 
(
   SELECT country, MAX(created_on) AS latest 
   FROM tax GROUP BY country
) t4 ON t1.created_on=t4.latest AND t1.country=t4.country;

表格

+-------------+--------------+------+-----+-------------------+-----------------
------------+

| Field       | Type         | Null | Key | Default           | Extra
            |

+-------------+--------------+------+-----+-------------------+-----------------
------------+

| id          | int(11)      | NO   | PRI | NULL              | auto_increment
            |

| country     | int(11)      | NO   |     | NULL              |
            |

| tax         | decimal(8,5) | NO   |     | NULL              |
            |

| created_by  | int(11)      | NO   |     | NULL              |
            |

| created_on  | timestamp    | NO   |     | CURRENT_TIMESTAMP |
            |

| modified_by | int(11)      | YES  |     | NULL              |
            |

| modified_on | timestamp    | YES  |     | NULL              | on update CURREN
T_TIMESTAMP |

+-------------+--------------+------+-----+-------------------+-----------------
------------+

创建表查询：（我在 SQL Fiddle 中尝试过）

CREATE TABLE tax ( id int(11) NOT NULL AUTO_INCREMENT, country int(11) NOT NULL, tax decimal(8,5) NOT NULL, created_by int(11) NOT NULL, created_on timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, modified_by int(11) DEFAULT NULL, modified_on timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP, PRIMARY KEY (id) );

INSERT INTO tax(country, tax, created_by, created_on) VALUES (1,7,51,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (1,7,51,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (1,7,49,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (1,7,50,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (1,7,48,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (6,9.45450,51,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (3,8.88900,49,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (2,9.08989,49,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (2,4.00087,49,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (1,1.88900,49,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (4,5.54656,51,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (5,7.45435,50,'2015-06-26 16:26:20');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (1,43.88776,46,'2015-06-26 17:30:18');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (2,5.67,46,'2015-06-26 17:39:12');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (12,0.009,46,'2015-06-26 17:48:35');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (11,3,46,'2015-06-26 17:55:14');
INSERT INTO tax(country, tax, created_by, created_on) VALUES (1,5,46,'2015-06-26 17:55:39');

请找SQL Fiddle Result @

结果在 phpmyadmin(localhost) 中产生

+----+---------+---------+------------+---------------------+-------------+-----
--------+

| id | country | tax     | created_by | created_on          | modified_by | modi
fied_on |

+----+---------+---------+------------+---------------------+-------------+-----
--------+

|  3 |       3 | 7.00000 |         49 | 2015-06-26 16:26:20 |        NULL | NULL
        |

|  5 |       5 | 7.00000 |         48 | 2015-06-26 16:26:20 |        NULL | NULL
        |

|  6 |       6 | 9.45450 |         51 | 2015-06-26 16:26:20 |        NULL | NULL
        |

|  7 |       3 | 8.88900 |         49 | 2015-06-26 16:26:20 |        NULL | NULL
        |

| 11 |       4 | 5.54656 |         51 | 2015-06-26 16:26:20 |        NULL | NULL
        |

| 12 |       5 | 7.45435 |         50 | 2015-06-26 16:26:20 |        NULL | NULL
        |

| 14 |       2 | 5.67000 |         46 | 2015-06-26 17:39:12 |        NULL | NULL
        |

| 15 |      12 | 0.00900 |         46 | 2015-06-26 17:48:35 |        NULL | NULL
        |

| 16 |      11 | 3.00000 |         46 | 2015-06-26 17:55:14 |        NULL | NULL
        |

| 17 |       1 | 5.00000 |         46 | 2015-06-26 17:55:39 |        NULL | NULL
        |

+----+---------+---------+------------+---------------------+-------------+-----
--------+

【问题讨论】：

获得不同结果的明显原因是您使用不同的源数据。在 phpmyadmin 的示例输出中，与 sql fiddle 一起使用的数据集中没有两行。

哦，我的坏。你说的对？现在我得到两个结果相同@jpw

能否帮我编写查询以获取每个country 的所有最新tax 而不会重复？

查询不就是这样吗？

@jpw 是但是。如果您在 Result Produced in phpmyadmin(localhost) 中看到 country 列，则表 ID 3 和 5 重复。我只想要每个country 的最新tax。

【参考方案1】：

查看此链接以查看错误日志的内容。

这是非常错误的，因为这些结果甚至没有意义。 where can I find mysql logs in phpmyadmin?

还可以查看简单的选择语句是否正常工作。