Select sum of an array column in PostgreSQL

Question

If I have the following table:

Table \"users\"
Column          |       Type       | Modifiers 
---------------+------------------+-----------
  id            | i         


        

Answer 1

This generalization and reformatting Dmitry's answer helps me understand how it works:

SELECT
  sum(a) AS total
FROM
  (
    SELECT
      unnest(array [1,2,3]) AS a
  ) AS b

Result:

total
 6