How to save data to a variable in an UPDATE query in a PostgreSQL function?

Question

PostgreSQL

As it is correct to save the data in a variable in plpgsql, I try so:
DECLARE
c INTEGER;
UPDATE table SET col = (c := col + 1) WHERE id = 1;
(further variable "c" is used in other queries)
Error:
ERROR: syntax error at or near ":="

Answer 1

UPDATE ... returning
www.postgresql.org/docs/9.4/static/sql-update.html