Oracle SQL：如何合并n行并在结果中创建其他列？

Question

表格：

id race
1  elf
1  troll
2  lizard
2  elf
2  human    
3  dwarf

我正在寻找一个输出以下内容的请求：

id race1   race2   race3
1  elf     troll   
2  lizard  elf     human
3  dwarf

如果更容易的话，可以有n个种族或给定的最大种族数

使用SQL查询（不是pl / sql）可以吗？ （如果需要特殊功能，则为Oracle）

Answer 1

如果要在简单的select中进行此操作，则可以使用条件聚合：

select id,
       max(case when seqnum = 1 then race end) as race_1,
       max(case when seqnum = 2 then race end) as race_2,
       max(case when seqnum = 3 then race end) as race_3,
       max(case when seqnum = 4 then race end) as race_4,
       max(case when seqnum = 5 then race end) as race_5
from (select t.*,
             row_number() over (partition by id order by id) as seqnum
      from t
     ) t
group by id;