Oracle正则表达式-不以且不以 [英] Oracle regex - does not start with and does not end with

问题描述

以下Oracle正则表达式不起作用，我也不知道为什么.

The following Oracle regular expressions do not work and I don't know why.

不以' abc '开头":

^[^(abc)]

不以' abc '结尾"

[^(abc)]$

问题是Oracle正则表达式引擎似乎无法将'abc'字符串识别为一个单元，而只是单独查看字母.括号()应该创建一个字符串单元.所以我不知道发生了什么.我之所以使用方括号，是因为我相信'not'运算符^只能在方括号内进行运算，否则^被识别为行首.

The problem is that the Oracle regex engine does not seem to recognize the 'abc' string as a unit, but only is looking at the letters individually. The parentheses () are supposed to create a string unit. So I don't know what is going on. I used the square brackets only because I believe the 'not' operator ^ only operates inside the brackets, otherwise the ^ is recognized as start of line.

供参考: http://docs.oracle.com/cd/B12037_01/appdev .101/b10795/adfns_re.htm

推荐答案

像这样的不匹配测试可能会变得很复杂，因此，我建议测试匹配并否定结果.

Testing for non-matching like this can get complicated, so I'd recommend testing for a match and negating the result.

不是以abc开头:

WHERE NOT REGEXP_LIKE(myString, '^abc')

不以abc结尾:

WHERE NOT REGEXP_LIKE(myString, 'abc$')

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至于为什么它不起作用，正如@DavidKnipe在他的回答中所说:这是因为您正在使用字符类.正则表达式^[^(abc)]解析如下:

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As for why it doesn't work, as @DavidKnipe says in his answer: it's because you're using character classes. The regex ^[^(abc)] parses out like this:

• 第一个^说锚定到字符串的开头"
• [^(abc)]是一个字符类，它说匹配任何单个字符，只要它不是(或a或b或c或)"

• The first ^ says "anchor to the beginning of the string"
• The [^(abc)] is a character class that says "match any single character as long as it's not ( or a or b or c or )".

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