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

This is a more generic answer to 'how to get the last element of an array'.

trader=# create table temp (name varchar);
CREATE TABLE

trader=# insert into temp (name) values ('foo bar baz');
INSERT 0 1

trader=# select (regexp_split_to_array(name, ' ')) from temp;
 regexp_split_to_array 
-----------------------
 {foo,bar,baz}
(1 row)

trader=# select (regexp_split_to_array(name, ' '))[array_upper(regexp_split_to_array(name, ' '), 1)] from temp;
 regexp_split_to_array 
-----------------------
 baz
(1 row)

array_upper

Returns the index of the last element of an array. So to use it, you have to reference the array twice: some_array[array_upper(some_array, 1)]

---

So if you already have your array:

trader=# create view temp2 as  (select regexp_split_to_array(name, ' ') as name_parts from temp);
CREATE VIEW

trader=# select * from temp2;
  name_parts   
---------------
 {foo,bar,baz}
(1 row)

It's less verbose to select the last element:

trader=# select name_parts[array_upper(name_parts, 1)] from temp2;
 name_parts 
------------
 baz
(1 row)