Question

样本表

Child    Parent
FF00001  12345
AA00002  12345
GG00003  12345
TT00003  12345

我想要的是这样的表

Parent  FF        AA        GG      TT 
12345  FF00001    AA00002  GG00003  TT00003

前2个字母后面的数字可以是任何东西，但我知道它们总是AA，FF，GG，TT等。我可以转向类似的声明吗？ like 'AA%'

Answer 1

您可以使用这样的聚合：

select
    parent,
    max(case when child like 'FF%' then child end) FF,
    max(case when child like 'AA%' then child end) AA,
    max(case when child like 'GG%' then child end) GG,
    max(case when child like 'TT%' then child end) TT 
from your_table
group by parent;

其他方法是使用substr在子查询中查找前缀，然后在其上应用pivot。

select *
from (
    select
        child,
        parent,
        substr(child, 1, 2) prefix
    from your_table
)
pivot (
    max(child) for prefix in ('FF' as FF,'AA' as AA,'GG' as GG,'TT' as TT)
)

两者都产生：

PARENT  FF      AA      GG      TT
---------------------------------------
12345   FF00001 AA00002 GG00003 TT00003

如果您有多个具有相同前缀的值并且想要全部保留它们，请在子查询中使用row_number()窗口函数，然后应用pivot：

with your_table (Child   , Parent) as (
    select 'FF00001', 12345 from dual union all
    select 'FF00002', 12345 from dual union all
    select 'AA00002', 12345 from dual union all
    select 'GG00003', 12345 from dual union all
    select 'TT00003', 12345 from dual
)
-- test data setup ends. See the solution below --

select parent, FF, AA, GG, TT
from (
    select
        child,
        parent,
        substr(child, 1, 2) prefix,
        row_number() over (partition by parent, substr(child, 1, 2) order by child)
    from your_table
)
pivot (
    max(child) for prefix in ('FF' as FF,'AA' as AA,'GG' as GG,'TT' as TT)
)

产地：

PARENT  FF      AA      GG      TT
---------------------------------------
12345   FF00001 AA00002 GG00003 TT00003
12345   FF00002  -       -       -

Oracle使用like基于列值来转动表

1 个答案: