将ROWS分成多个COLUMN

Question

我有一些有关学生姓名及其名册的信息-

我想将它们分成3组，如下所示。总行数应始终为（3行数/ 3）的上限值

Answer 1

您可以通过条件聚合来做到这一点。但是，SQL表表示无序集，因此哪些值最终在任意位置：

select max(case when seqnum % 3 = 0 then name end) as name_1,
       max(case when seqnum % 3 = 0 then roll end) as roll_1,
       max(case when seqnum % 3 = 1 then name end) as name_2,
       max(case when seqnum % 3 = 1 then roll end) as roll_2,
       max(case when seqnum % 3 = 2 then name end) as name_3,
       max(case when seqnum % 3 = 2 then roll end) as roll_3       
from (select t.*, row_number() over (order by (select null)) - 1 as seqnum
      from t
     ) t
group by floor(seqnum / 3);

如果您有订购栏，请使用它代替(select null)。