具有相同通配符的模式匹配 [英] Pattern matching with identical wildcards

问题描述

我正在使用 PostgreSQL，想知道您是否可以让通配符保留其值.

I'm working with PostgreSQL and want to know whether you can have a wildcard retain its value.

例如说我有

select * from tableOne where field like ‘_DEF_’;

有没有办法让第一个和最后一个通配符完全相同?

Is there a way to get the first and last wildcard to be the exact same character?

因此示例匹配结果可能是:ADEFA 或 ZDEFZ.

So an example matching result could be: ADEFA or ZDEFZ.

推荐答案

您可以使用带有反向引用的正则表达式:

You can use a regular expression with a back-reference:

select * 
from some_table
where some_column ~* '^(.)DEF(\1)$'

^(.)DEF(\1)$ 表示:开头的某个字符后跟 DEF 后跟第一个字符必须出现在字符串的末尾.

^(.)DEF(\1)$ means: some character at the beginning followed DEF followed by the first character must occur at the end of the string.

() 定义了一个组，\1 引用了第一个组(在这个例子中是输入序列中的第一个字符)

The () defines a group and the \1 references the first group (which is the first character in the input sequence in this example)

SQLFiddle 示例:http://sqlfiddle.com/#!15/d4c4d/1

SQLFiddle example: http://sqlfiddle.com/#!15/d4c4d/1

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