DROP TABLE emps;

CREATE TABLE emps(userid int PRIMARY KEY, age int, salary numeric );

INSERT INTO emps VALUES(10, 25, 1000.0),(11, 26, 1500.0),(12, 27, 1300.0),(13, 35, 3000.0), (14, 45, 4000.0);

    DROP FUNCTION IF EXISTS add_salary(_bonus numeric );

    CREATE OR REPLACE FUNCTION add_salary(_bonus numeric )

    RETURNS numeric AS $body$

    DECLARE

        level1 numeric  := 30;

        level2 numeric  :=40;

        res numeric  := 0;

        page int;

        puserid int;

        mycursor refcursor ;

        BEGIN

            OPEN mycursor FOR SELECT userid, age FROM emps;

            FETCH mycursor INTO puserid, page;

            RAISE NOTICE 'age is :----%',puserid||','||page;

            WHILE FOUND LOOP

                IF  page <= level1

                THEN

                    UPDATE emps SET salary = salary * 1.1 WHERE userid = puserid;

                ELSIF  page > level1 AND page <= level2

                THEN

                    UPDATE emps SET salary = salary*1.2 WHERE userid = puserid;

                ELSE

                    UPDATE emps SET salary = salary*1.3 WHERE userid = puserid;

                END IF;        

                FETCH mycursor INTO puserid, page;

            END LOOP;

                SELECT AVG(SALARY) FROM emps INTO res;

                RETURN res;

        END

    $body$

    Language plpgsql;