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 Postgr

Answer 1

Q: what I want to do is to sort by the last word of a specific column

When dealing with an actual array of text (not a string), use array_upper() in the index.

Demo for 1-dimensional array

WITH x(a) AS (
    VALUES
       ('{zoo, zar, zaz}'::text[])
      ,('{3,4,5,6}')
      ,('{foo, bar, baz}')
    )
SELECT *
FROM   x
ORDER  BY a[array_upper(a, 1)];

Demo for 2-dimensional array

WITH x(a) AS (
    VALUES
       ('{{zoo, zar, zaz}
         ,{4,5,6}
         ,{14,15,16}
         ,{foo, bar, zzzaz}}'::text[])
      ,('{{zoo, zar, baz}
         ,{4,5,6}
         ,{14,15,16}
         ,{foo, bar, aaaaz}}'::text[])
    )
SELECT *
FROM   x
ORDER  BY a[array_upper(a, 1)][array_upper(a, 2)];