Getting the last word from a Postgres string, declaratively

Question

[EDIT] original title of this question was "Getting the last element of a Postgres array, declaratively"

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

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.

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.

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?

Answer 1

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.

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

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

Result:

baz 

Answer 2

Use array_upper():

SELECT array_upper(ARRAY[1,2,5,6], 1);