hivesql 多行转多列

with t1 as (select 1 as student, "math" as ck, 3 as sub union all select 3 as student, "math" as ck,3 as sub
   union all select 5 as student, "math2" as ck , 4 as sub)

select student,
        max(ck_pv) as math,
        max(ck2_pv) as math2
from (
    select student,
            if(ck = "math", sub, 0 ) as ck_pv,
            if(ck = "math2", sub,0 ) as ck2_pv
    from t1
)
group by student

多行转移一列 ：concat(a,',',b) collect_set/collect_list groupby