MySQL正则表达式方括号的元字符列表 [英] List of metacharacters for MySQL regexp square brackets

问题描述

奇怪的是，我似乎无法在任何地方找到我无法安全地用作MySQL正则表达式方括号内的文字的字符列表，而不会转义它们或要求使用[:character_class:]东西.

Strangely I can't seem to find anywhere a list of the characters that I can't safely use as literals within MySQL regular expression square brackets without escaping them or requiring the use of a [:character_class:] thing.

(答案也可能需要特定于MySQL，因为与Perl/PHP/Javascript等相比，MySQL正则表达式似乎缺乏).

(Also the answer probably needs to be MySQL specific because MySQL regular expressions seem to be lacking compared those in Perl/PHP/Javascript etc).

推荐答案

几乎所有元字符(包括点.，+，*和?量词，字符串结尾锚$等)在字符类中没有特殊含义，但有一些值得注意的例外:

Almost all metacharacters (including the dot ., the +, * and ? quantifiers, the end-of-string anchor $, etc.) have no special meaning in character classes, with a few notable exceptions:

• 右方括号]，
• 插入符号^，用于否定字符类(例如:[^ab]匹配任何字符但 a和b).
• 连字符-，用于表示范围(例如:[0-9]匹配任何数字)

• closing bracket ], for obvious reasons
• caret ^, which is used to negate the character class (eg: [^ab] matches any character but a and b).
• hyphen -, which is used to denote a range (eg: [0-9] matches any digit)

但是，如果将它们放置在角色类中的重要位置，则仍可以在不逃避的情况下添加它们:

However, these can still be added without escaping if placed in strategic locations within the character class:

• 可以将闭合括号放在打开括号之后，例如:[]a]匹配]或a.
• 插入符可以放置在左括号之后的任何位置，例如，例如:[a^]匹配^或a
• 连字符可以放在左括号或右括号之前，例如:[-a]和[a-]都与a和-匹配.

• the closing bracket can be placed right after the opening bracket, eg: []a] matches ] or a.
• the caret can be placed anywhere but after the opening bracket, eg: [a^] matches ^ or a
• the hyphen can be placed right after the opening bracket or before the closing bracket, eg: [-a] and [a-] both match a and -.

更多信息可以在 POSIX的手册页中找到. regex (感谢Tomalak Geret'kal！)

More information can be found in the man page on POSIX regex (thanks Tomalak Geret'kal!)

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