固定列数的行列转换如
student subject grade---------------------------student1 语文 80student1 数学 70student1 英语 60student2 语文 90student2 数学 80student2 英语 100转换为student 语文 数学 英语student1 80 70 60student2 90 80 100语句如下：select student,sum(decode(subject,'语文', grade,null)) "语文",sum(decode(subject,'数学', grade,null)) "数学",sum(decode(subject,'英语', grade,null)) "英语"from tablegroup by student
