How to use dblink for update?
SELECT INTO DUMMY dblink_connect('host=localhost  port=5432 dbname=DBNAME user=USERNAME password=PASSWORD');
    SELECT INTO DUMMY dblink_open('PARAMS', 'SELECT VALUE FROM TABLE');
            LOOP
              SELECT INTO ONE_PARAM RES.VALUE FROM (SELECT * FROM dblink_fetch(''PARAMS'', 1) AS (VALUE VARCHAR(100))) RES;
                EXIT WHEN NOT FOUND;
                /*DO UPDATE HERE*/
            END LOOP;
            SELECT INTO DUMMY dblink_close(''PARAMS'');