如何在MySQL中搜索斜杠（\）？为什么逃避（\）不需要在哪里（=），但对于喜欢是必需的？ [英] How to search for slash (\) in MySQL? and why escaping (\) not required for where (=) but for Like is required?

问题描述

考虑这个QUERY（ DEMO在这里）

Consider this QUERY (DEMO IS HERE)

(SELECT * FROM `titles` where title = 'test\\')
UNION ALL
(SELECT * FROM `titles` where title LIKE 'test\\\\')

输出：

| ID | TITLE |
--------------
|  1 | test\ |
|  1 | test\ |

QUESTION：

（=）需要强度（\），但是（如）需要附加的 \\ ？
它清楚的是，MySQL使用（test\\）转义了（test\），然后使用（test\\\

QUESTION:

Why no extra (\) required for (=) but for (like) additional \\ is required? Its clear that MySQL escaped the (test\) with (test\\) then using (test\\\\) is logical for LIKE.

表信息：

CREATE TABLE IF NOT EXISTS `titles` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(255) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=7 ;

--
-- Dumping data for table `titles`
--

INSERT INTO `titles` (`id`, `title`) VALUES
(1, 'test\\');

推荐答案

\ 在 LIKE 中作为转义字符，默认情况下。

\ functions as an escape character in LIKE by default.

从手册 for LIKE ：

由于MySQL在字符串中使用C转义语法（例如，\\\
表示换行符），则必须将任何\ 你在LIKE字符串中使用例如，要搜索\\\
，请将其指定为\\\\
。要搜索\，请将其指定为\\\\;这是因为当模式匹配时，解析器和再次剥离反斜杠，留下一个反斜杠与之匹配。

Because MySQL uses C escape syntax in strings (for example, "\n" to represent a newline character), you must double any "\" that you use in LIKE strings. For example, to search for "\n", specify it as "\\n". To search for "\", specify it as "\\\\"; this is because the backslashes are stripped once by the parser and again when the pattern match is made, leaving a single backslash to be matched against.

您可以通过指定另一个转义字符来更改此值，如：

You can change this by specifying another escape character, as in:

SELECT * FROM `titles` where title LIKE 'test\\' ESCAPE '|'

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