presto行转列

presto的行列转换和spark、hive一样也是通过外链语句实现的，只不过语法和关键子有点不同，如下

with tmp1 as (
    select '1,2,3' as a1,'4,5,6' as a2
)
select * from tmp1 cross join unnest(
    split(tmp1.a1, ','),
    split(tmp1.a2, ',')
) as b(a1s,a2s) 

结果如下