postgresql正则表达式和子字符串

发布于 2024-10-17 14:15:42 字数 446 浏览 2 评论 0原文

我有一个正则表达式 http\:\/\/domainname\.com\/\S{4} 应该捕获如下网址： http://domainname.com/key4< /code> 较长的文本。

我只想获取密钥并将其与 postgres 数据库中的表字段进行匹配。

在尝试了一些东西之后，我来到了这个查询（用于获取密钥）：

SELECT substring(infos FROM '[http\:\/\/domainname\.com\/\S{4}]{7}' ) AS key FROM actions

结果我得到了每行的 /domainname.com ...好吧，没有你所看到的密钥。

我做错了什么？

谁能告诉我 {7} 代表什么？

原文

I have a regular expression http\:\/\/domainname\.com\/\S{4} which should catch urls like this: http://domainname.com/key4 in a longer text.

I want to get only the key and match it with a table field in my postgres database.

after trying some stuff I came to this query (for grabbing keys):

SELECT substring(infos FROM '[http\:\/\/domainname\.com\/\S{4}]{7}' ) AS key FROM actions

as a result i get the /domainname.com for each row ... well, no keys as you can see.

what am I doing wrong?

can anyone tell me what the {7} stands for?

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

怪我入戏太深 2024-10-24 14:15:43

{7} 代表之前模式的 7 倍。因此，在本例中，[ 和 ] 之间存在不同的字符。即 [abc]{3} 匹配 aaa cba 或任何其他组合。

我相当确定这不是您想要的。您可能正在寻找类似的东西：

SELECT substring('http://domainname.com/key4' from 'http://domainname\\.com/\\S{4}')
FROM actions

The {7} stands for 7 times the previous pattern. So in this case, the different characters between [ and ]. i.e. [abc]{3} matches aaa cba or any other combination.

I'm fairly certain that this is not what you want. You are probably looking for something like this instead:

SELECT substring('http://domainname.com/key4' from 'http://domainname\\.com/\\S{4}')
FROM actions

回复收藏 0 原文

噩梦成真你也成魔 2024-10-24 14:15:43

这可能是您在这种特定情况下正在寻找的内容，

select substring(substring('long text [http://domainname.com/key4] more text',E'http\:\/\/domainname\.com\/\\S{4}'),E'\\S{4}
如果它是四个字符长，它将提取关键部分。如果您可能也在寻找类似 key456 的内容，那么更通用的匹配
select substring(substring('long text [http://domainname.com/key467] more text',E'http\:\/\/domainname\.com\/key\\d+'),E'key\\d+
可能更合适
);

如果它是四个字符长，它将提取关键部分。如果您可能也在寻找类似 key456 的内容，那么更通用的匹配

可能更合适
);

可能更合适

);

如果它是四个字符长，它将提取关键部分。如果您可能也在寻找类似 key456 的内容，那么更通用的匹配

可能更合适

This might be what you are looking for in this specific case

select substring(substring('long text [http://domainname.com/key4] more text',E'http\:\/\/domainname\.com\/\\S{4}'),E'\\S{4}
which will extract the key part if it is four characters long. If you might also be looking for something like key456 then a more generic match such as 
select substring(substring('long text [http://domainname.com/key467] more text',E'http\:\/\/domainname\.com\/key\\d+'),E'key\\d+
may be more appropriate
);

which will extract the key part if it is four characters long. If you might also be looking for something like key456 then a more generic match such as 

may be more appropriate
);

may be more appropriate

);

which will extract the key part if it is four characters long. If you might also be looking for something like key456 then a more generic match such as

may be more appropriate

回复收藏 0 原文

~没有更多了~