Question

我有一个PHP脚本，可根据您从下拉框中选择的内容生成报告。第一个选项是“全部”。如果选择“全部”选项，则得到的结果将不同于选择特定选项的结果。它是同一条sql语句，唯一的区别是：

and service_name like 'enf%'
and service_name like '%%'

第一个给我16个结果（以'enf'开头），第二个给我13个结果以'enf'开头。这毫无意义！

完整的陈述（如回显）是：

select service_name,order_section from transcription_result where flags='Exported' and exported between '20180801000000' and '20180831235959' and service_name like 'enf%' group by order_section order by service_name, order_section ASC

select service_name,order_section from transcription_result where flags='Exported' and exported between '20180801000000' and '20180831235959' and service_name like '%%' group by order_section order by service_name, order_section ASC

我尝试过...

and service_name like '%%'

...从第二条语句中删除，但得到相同的错误结果。

数据库服务器版本为10.1.25-MariaDB-源分发 Apache / 2.4.26（Unix）OpenSSL / 1.0.2l PHP / 5.6.31 mod_perl / 2.0.8-dev Perl / v5.16.3 PHP版本：5.6.31 phpmyadmin版本信息：4.7.0，最新稳定版本：4.8.3 Ubuntu 16.04.4 LTS

表的模式：

`id` int(11) NOT NULL,
`session_id` varchar(100) NOT NULL,
`caller_id` varchar(20) DEFAULT NULL,
`service_name` varchar(20) NOT NULL,
`order_section` varchar(100) NOT NULL,
`variable_name` varchar(50) NOT NULL,
`variable_value` longtext NOT NULL,
`flags` varchar(50) NOT NULL COMMENT 'E- empty, R- Review',
`exported` timestamp NULL DEFAULT NULL,
`transcribed` timestamp NULL DEFAULT NULL,
`session_tbl_id` int(11) DEFAULT NULL,
`transcribed_by` varchar(50) NOT NULL,
`time_taken` int(3) NOT NULL COMMENT 'in seconds',
`timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

解决方案

我将声明更改为：

select distinct(order_section), service_name from transcription_result where flags='Exported' and exported between '20180801000000' and '20180831235959' and service_name like '%%' order by service_name, order_section ASC

Answer 1

根据给定的架构，这是对问题的最小复制：

INSERT INTO transcription_result
            (flags,
             exported,
             service_name,
             order_section)
VALUES      ('Exported',
             '20180805',
             'zzz12345',
             'one');

INSERT INTO transcription_result
            (flags,
             exported,
             service_name,
             order_section)
VALUES      ('Exported',
             '20180805',
             'enf12345',
             'one');

INSERT INTO transcription_result
            (flags,
             exported,
             service_name,
             order_section)
VALUES      ('Exported',
             '20180805',
             'enf12345',
             'two');

INSERT INTO transcription_result
            (flags,
             exported,
             service_name,
             order_section)
VALUES      ('Exported',
             '20180805',
             'zzz12345',
             'two');  


SELECT service_name,
       order_section
FROM   transcription_result
WHERE  flags = 'Exported'
       AND exported BETWEEN '20180801000000' AND '20180831235959'
       AND service_name LIKE 'enf%'
GROUP  BY order_section
ORDER  BY service_name,
          order_section ASC;  

+--------------+---------------+
| service_name | order_section |
+--------------+---------------+
| enf12345     | one           |
| enf12345     | two           |
+--------------+---------------+
2 rows in set (0.01 sec)

SELECT service_name,
       order_section
FROM   transcription_result
WHERE  flags = 'Exported'
       AND exported BETWEEN '20180801000000' AND '20180831235959'
       AND service_name LIKE '%%'
GROUP  BY order_section
ORDER  BY service_name,
          order_section ASC;  
+--------------+---------------+
| service_name | order_section |
+--------------+---------------+
| enf12345     | two           |
| zzz12345     | one           |
+--------------+---------------+
2 rows in set (0.00 sec)

我希望这能说明问题，并表明group by是基本问题-因为service_name不是由查询确定的。许多种SQL拒绝这些查询，但是MySQL允许它们运行，这通常很方便，有时会造成混淆。

使用MAX(service_name)之类的聚合函数可以解决不确定的查询问题。

Answer 2

我删除了“分组依据”并添加了“与众不同”：

select distinct(order_section), service_name from transcription_result where flags='Exported' and exported between '20180801000000' and '20180831235959' and service_name like '%%' order by service_name, order_section ASC

Answer 3

替代解决方案。如果您对所有列进行“分组”，您还将获得正确的结果：

select order_section, service_name from transcription_result where flags='Exported' and exported between '20180801000000' and '20180831235959' and service_name like '%%' group by service_name,order_section order by service_name, order_section ASC

mysql通配符（％）在不使用通配符时给出不同的结果

3 个答案: