Sql 在oracle中查找根父级的递归查询
我试图在一个具有分层数据的表中找出根父级。下面的示例按预期工作，但我需要做一些额外的事情。我希望避免查询忽略null id1，并在根父项为null时显示（根父项-1）Sql 在oracle中查找根父级的递归查询,sql,recursion,Sql,Recursion,我试图在一个具有分层数据的表中找出根父级。下面的示例按预期工作，但我需要做一些额外的事情。我希望避免查询忽略null id1，并在根父项为null时显示（根父项-1） with table_a ( id1, child_id ) as ( select null, 1 from dual union all select 1, 2 from dual union all select 2, 3 from dual union all
with table_a ( id1, child_id ) as (
select null, 1 from dual union all
select 1, 2 from dual union all
select 2, 3 from dual union all
select 3, NULL from dual union all
select 4, NULL from dual union all
select 5, 6 from dual union all
select 6, 7 from dual union all
select 7, 8 from dual union all
select 8, NULL from dual
)
select connect_by_root id1 as id, id1 as root_parent_id
from table_a
where connect_by_isleaf = 1
connect by child_id = prior id1
order by id 1
This brings up the following data
4 4
6 5
7 5
8 5
5 5
3 null
null null
2 null
1 null
what I want is
3 1
1 1
2 1
4 4
7 5
8 5
5 5
6 5
is it possible?
Thanks for the help
这看起来是可行的，但可能是不正确的，因为我不太理解选择1的逻辑，在我看来是任意的，与实际数据不太一样。 正如Hogan已经提出的，如果您可以提供一个解释或扩展的数据集来测试这个层次结构，这将是很有帮助的
with table_a ( id1, child_id ) as (
select null, 1 from dual union all
select 1, 2 from dual union all
select 2, 3 from dual union all
select 3, NULL from dual union all
select 4, NULL from dual union all
select 5, 6 from dual union all
select 6, 7 from dual union all
select 7, 8 from dual union all
select 8, NULL from dual
)
select connect_by_root id1 as id, id1 as root_parent_id
from table_a
where connect_by_isleaf = 1 and connect_by_root id1 is not null
connect by nocycle child_id = prior nvl(id1, 1)
order by 2, 1;
FSITJA@dbd01 2019-07-19 13:51:13> with table_a ( id1, child_id ) as (
2 select null, 1 from dual union all
3 select 1, 2 from dual union all
4 select 2, 3 from dual union all
5 select 3, NULL from dual union all
6 select 4, NULL from dual union all
7 select 5, 6 from dual union all
8 select 6, 7 from dual union all
9 select 7, 8 from dual union all
10 select 8, NULL from dual
11 )
12 select connect_by_root id1 as id, id1 as root_parent_id
13 from table_a
14 where connect_by_isleaf = 1 and connect_by_root id1 is not null
15 connect by nocycle child_id = prior nvl(id1, 1)
16 order by 2, 1;
ID ROOT_PARENT_ID
---------- --------------
1 1
2 1
3 1
4 4
5 5
6 5
7 5
8 5
8 rows selected.
这看起来是可行的，但可能是不正确的，因为我不太理解选择1的逻辑，在我看来是任意的，与实际数据不太一样。 正如Hogan已经提出的，如果您可以提供一个解释或扩展的数据集来测试这个层次结构，这将是很有帮助的
with table_a ( id1, child_id ) as (
select null, 1 from dual union all
select 1, 2 from dual union all
select 2, 3 from dual union all
select 3, NULL from dual union all
select 4, NULL from dual union all
select 5, 6 from dual union all
select 6, 7 from dual union all
select 7, 8 from dual union all
select 8, NULL from dual
)
select connect_by_root id1 as id, id1 as root_parent_id
from table_a
where connect_by_isleaf = 1 and connect_by_root id1 is not null
connect by nocycle child_id = prior nvl(id1, 1)
order by 2, 1;
FSITJA@dbd01 2019-07-19 13:51:13> with table_a ( id1, child_id ) as (
2 select null, 1 from dual union all
3 select 1, 2 from dual union all
4 select 2, 3 from dual union all
5 select 3, NULL from dual union all
6 select 4, NULL from dual union all
7 select 5, 6 from dual union all
8 select 6, 7 from dual union all
9 select 7, 8 from dual union all
10 select 8, NULL from dual
11 )
12 select connect_by_root id1 as id, id1 as root_parent_id
13 from table_a
14 where connect_by_isleaf = 1 and connect_by_root id1 is not null
15 connect by nocycle child_id = prior nvl(id1, 1)
16 order by 2, 1;
ID ROOT_PARENT_ID
---------- --------------
1 1
2 1
3 1
4 4
5 5
6 5
7 5
8 5
8 rows selected.
使用递归CTE，您可以执行以下操作：
with table_a ( id1, child_id ) as (
select null, 1 from dual union all
select 1, 2 from dual union all
select 2, 3 from dual union all
select 3, NULL from dual union all
select 4, NULL from dual union all
select 5, 6 from dual union all
select 6, 7 from dual union all
select 7, 8 from dual union all
select 8, NULL from dual
),
n (s, e) as (
select id1 as s, child_id as e from table_a where id1 not in
(select child_id from table_a
where id1 is not null and child_id is not null)
union all
select n.s, a.child_id
from n
join table_a a on a.id1 = n.e
)
select
coalesce(e, s) as c, s
from n
order by s
C S
- -
3 1
1 1
2 1
4 4
5 5
7 5
8 5
6 5
作为旁注，“递归CTE”比旧式的
connectbywith table_a ( id1, child_id ) as (
select null, 1 from dual union all
select 1, 2 from dual union all
select 2, 3 from dual union all
select 3, NULL from dual union all
select 4, NULL from dual union all
select 5, 6 from dual union all
select 6, 7 from dual union all
select 7, 8 from dual union all
select 8, NULL from dual
),
n (s, e) as (
select id1 as s, child_id as e from table_a where id1 not in
(select child_id from table_a
where id1 is not null and child_id is not null)
union all
select n.s, a.child_id
from n
join table_a a on a.id1 = n.e
)
select
coalesce(e, s) as c, s
from n
order by s
C S
- -
3 1
1 1
2 1
4 4
5 5
7 5
8 5
6 5
作为旁注，“递归CTE”比旧式的
connectby