SQL整理十一

学生信息表：studentinfo
+----+---------+-------+
|name   kecheng  fenshu
|张三     语文       81 
|张三     数学       75 
|李四     语文       76 
|李四     数学       90 
|王五     语文       81 
|王五     数学       100 
|王五     英语       90
+----+---------+-------+
SQL:
+-----------------------------------------------------+
DROP TABLE IF EXISTS `studentinfo`;   
CREATE TABLE `studentinfo` (   
  `Id` int(11) NOT NULL auto_increment,   
  `name` varchar(12) default NULL,   
  `kecheng` varchar(12) default NULL,   
  `fenshu` int(11) default NULL,   
  PRIMARY KEY  (`Id`)   
) ENGINE=MyISAM DEFAULT CHARSET=utf8;   
INSERT INTO `studentinfo` VALUES (1,'zhang','yu',81);   
INSERT INTO `studentinfo` VALUES (2,'zhang','shu',75);   
INSERT INTO `studentinfo` VALUES (3,'li','yu',76);   
INSERT INTO `studentinfo` VALUES (4,'li','shu',90);   
INSERT INTO `studentinfo` VALUES (5,'wang','yu',81);   
INSERT INTO `studentinfo` VALUES (6,'wang','shu',100);   
INSERT INTO `studentinfo` VALUES (7,'wang','wai',90);   
INSERT INTO `studentinfo` VALUES (8,'liu','yu',83);  
+-----------------------------------------------------+
问题：
1.用一条SQL语句 查询出每门课都大于80分的学生姓名 
+----------------------+
|SELECT DISTINCT name  | 
|FROM studentinfo      |
|WHERE name NOT IN (   | 
| SELECT name          |
| FROM studentinfo     |
| WHERE fenshu <= 80   |
| GROUP BY name);      |
+----------------------+