CREATE OR REPLACE FUNCTION log_in(uname text, passwd text) RETURNS SETOF users AS $$
    DECLARE
        r RECORD;
    BEGIN
        SELECT * INTO r FROM users WHERE username = uname AND password = passwd;
        IF FOUND THEN
            UPDATE users SET lastvisit = now(), visits = visits + 1 WHERE id = r.id;
            r.visits := r.visits + 1;
            RETURN NEXT r;
        END IF;
        RETURN;
    END;
$$ LANGUAGE plpgsql;