求一条sql

with t as
 (select 'zhangsan' stu, 'math' sub, 70 score
    from dual
  union all
  select 'zhangsan' stu, 'english' sub, 70 score
    from dual
  union all
  select 'zhangsan' stu, 'chinese' sub, 70 score
    from dual
  union all
  select 'lisi' stu, 'chinese' sub, 70 score
    from dual
  union all
  select 'lisi' stu, 'math' sub, 70 score
    from dual
  union all
  select 'lisi' stu, 'english' sub, 70 score
    from dual
  union all
  select 'wangwu' stu, 'english' sub, 70 score
    from dual
  union all
  select 'wangwu' stu, 'math' sub, 70 score
    from dual
  union all
  select 'wangwu' stu, 'chinese' sub, 70 score from dual)
select stu,
       sum(decode(sub, 'chinese', score, null)) chinese,
       sum(decode(sub, 'math', score, null)) math,
       sum(decode(sub, 'english', score, null)) english
  from t
 group by t.stu