以声明方式从Postgres字符串中获取最后一个单词 [英] Getting the last word from a Postgres string, declaratively

问题描述

该问题的原始标题是以声明方式获取Postgres数组的最后一个元素

如何获取在Postgres中数组的最后一个元素？

How to obtain the last element of the array in Postgres?

我需要声明性地进行操作，因为我想将其用作ORDER BY条件。我不想为此创建特殊的PGSQL函数，在这种情况下，对数据库的更改越少越好。

I need to do it declaratively as I want to use it as a ORDER BY criteria. I wouldn't want to create a special PGSQL function for it, the less changes to the database the better in this case.

事实上，我要做的是按包含多个单词的特定列的最后一个单词排序。更改模型不是这里的选择。

In fact, what I want to do is to sort by the last word of a specific column containing multiple words. Changing the model is not an option here.

换句话说，我要推送Ruby的 sort_by {| x | x.split [-1]} 进入数据库级别。我可以使用Postgres string_to_array 或 regexp_split_to_array 函数将值拆分为单词数组，然后如何获取其最后一个元素？

In other words, I want to push Ruby's sort_by {|x| x.split[-1]} into the database level. I can split a value into array of words with Postgres string_to_array or regexp_split_to_array functions, then how to get its last element?

推荐答案

如果我正确地理解了您的问题，则您有一个字符串，首先要在某个分隔符上将其拆分，然后再查找

If I understand your question correctly you have a string and you're first splitting it on some separator and then afterwards finding the last element of the array and discarding the rest.

您可能会错过中间人并直接获得最后一个元素：

You could miss out the middle man and get the last element directly:

SELECT regexp_replace('foo bar baz', '^.* ', '')

结果：

baz

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