如何将行数据透视到特定列 db2

Question

我想将表中的结果转换为新结构。 这样它就可以将所有子产品映射到父产品。

当前结果

Parent_Prod_Num|Child_Prod_Num|Child_Prod_Code|Child_Prod_Name
1|11|a123|a
1|12|b123|ab
1|13|c123|abc

预期结果

Parent_Prod_Num|Child_Prod_Num_1| Child_Prod_Code_1|Child_Prod_Name_1| Child_Prod_Num_2| Child_Prod_Code_2|Child_Prod_Name_2| Child_Prod_Num_3| Child_Prod_Code_3|Child_Prod_Name_3
1|11|a123|a|12|b123|ab|13|c123|abc

Answer 1

对于每个父级固定的最大子级数，您可以使用row_number() ，然后使用条件聚合进行透视：

select parent_prod_num,
    max(case when rn = 1 then child_prod_num  end) as child_prod_num_1,
    max(case when rn = 1 then child_prod_code end) as child_prod_code_1,
    max(case when rn = 1 then child_prod_name end) as child_prod_name_1,
    max(case when rn = 2 then child_prod_num  end) as child_prod_num_2,
    max(case when rn = 2 then child_prod_code end) as child_prod_code_2,
    max(case when rn = 2 then child_prod_name end) as child_prod_name_2,
    max(case when rn = 3 then child_prod_num  end) as child_prod_num_3,
    max(case when rn = 3 then child_prod_code end) as child_prod_code_3,
    max(case when rn = 3 then child_prod_name end) as child_prod_name_3
from (
    select t.*, row_number() over(partition by parent_prod_num order by child_prod_num) rn
    from mytable t
) t
group by parent_prod_num