Cursor fetches NULL for aggregate functions

DROP TABLE IF EXISTS t1;

DROP PROCEDURE IF EXISTS p1;

CREATE TABLE t1 (name VARCHAR(10), value INT);

INSERT INTO t1 VALUES ('a',1);

INSERT INTO t1 VALUES ('a',1);

INSERT INTO t1 VALUES ('a',1);

INSERT INTO t1 VALUES ('b',1);

INSERT INTO t1 VALUES ('b',1);

INSERT INTO t1 VALUES ('c',1);

DELIMITER $$

CREATE PROCEDURE p1 ()

BEGIN

  DECLARE done INT DEFAULT FALSE;

  DECLARE v_name VARCHAR(10);

  DECLARE v_total INT;

  DECLARE c CURSOR FOR SELECT name, SUM(value) AS total FROM t1 GROUP BY name;

  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

  OPEN c;

read_loop:

  LOOP

    FETCH c INTO v_name, v_total;

    IF done THEN

      LEAVE read_loop;

    END IF;

    SELECT v_name, v_total;

  END LOOP;

  CLOSE c;

END;

$$

DELIMITER ;

CALL p1();

DROP PROCEDURE p1;

DROP TABLE t1;

+--------+---------+

| v_name | v_total |

+--------+---------+

| a      |       3 |

+--------+---------+

1 row in set (0.00 sec)

+--------+---------+

| v_name | v_total |

+--------+---------+

| b      |       2 |

+--------+---------+

1 row in set (0.00 sec)

+--------+---------+

| v_name | v_total |

+--------+---------+

| c      |       1 |

+--------+---------+

1 row in set (0.00 sec)

+--------+---------+

| v_name | v_total |

+--------+---------+

| a      |    NULL |

+--------+---------+

1 row in set (0.00 sec)

+--------+---------+

| v_name | v_total |

+--------+---------+

| b      |    NULL |

+--------+---------+

1 row in set (0.00 sec)

+--------+---------+

| v_name | v_total |

+--------+---------+

| c      |    NULL |

+--------+---------+

1 row in set (0.00 sec)