Setting a variable in pgsql

variable.sql

-- least onerous option from here https://stackoverflow.com/questions/1490942/how-to-declare-a-variable-in-a-postgresql-query#16552441
set session my.vars.id = '%my_string%';

SELECT
	*
FROM
	my_table
WHERE
	field LIKE current_setting('my.vars.id')::text
	OR other_field LIKE current_setting('my.vars.id')::text