MySQL查询出2门及2门以上不及格者的平均成绩

CREATE TABLE `result` (
  `name` varchar(20) default NULL,
  `subject` varchar(20) default NULL,
  `score` tinyint(4) default NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
insert into result values
('张三','数学',90),
('张三','语文',50),
('张三','地理',40),
('李四','语文',55),
('李四','政治',45),
('王五','政治',30),
('赵六','语文',100),
('赵六','数学',99),
('赵六','品德',98);

select name,sum(score < 60) ,avg(score)  from result  group by name having sum(score<60) >=2;