ORACLE Recursive query - oracle

Question

I'm trying to build a recursive query and I'm facing a problem.
please find below my dataset
WITH table1 ( ID, Code, Label ) as(
SELECT 123, 'C1', 'LABEL_1' from dual UNION ALL
SELECT 1, 'C2', 'LABEL_2' from dual UNION ALL
SELECT 30, 'C3', 'LABEL_3' from dual UNION ALL
SELECT 44, 'C4', 'LABEL_4' from dual UNION ALL
SELECT 5, 'C5', 'LABEL_5' from dual
),
table2 ( ID, id_table1, code_child, label_child ) as (
SELECT 1, 123, 'C1_1','LABEL_1_1' from dual UNION ALL
SELECT 2, 123, 'C1_2','LABEL_1_2' from dual UNION ALL
SELECT 3, 123, 'C1_3','LABEL_1_3' from dual UNION ALL
SELECT 4, 123, 'C1_4','LABEL_1_4' from dual UNION ALL
SELECT 6, 30, 'C3_1','LABEL_3_1' from dual UNION ALL
SELECT 7, 30, 'C3_2','LABEL_3_2' from dual UNION ALL
SELECT 8, 30, 'C3_3','LABEL_3_3' from dual UNION ALL
SELECT 9, 30, 'C3_4','LABEL_3_4' from dual UNION ALL
SELECT 10, 5, 'C5_1','LABEL_5_1' from dual
),
hierarchy as (
Select
a.id, code, label, CODE_CHILD,id_table1
from table1 a
left join table2 b on b.id_table1 = a.ID
)
,recursive (base, id, code, label, CODE_CHILD,id_table1) as (
SELECT
id as base,
id,
code,
label,
CODE_CHILD,
id_table1
FROM hierarchy
UNION ALL
SELECT
previous_level.base,
current_level.id,
current_level.code,
current_level.label,
current_level.CODE_CHILD,
current_level.id_table1
FROM recursive previous_level,
hierarchy current_level
WHERE 1=1
and current_level.id = previous_level.id_table1
)
SELECT * FROM recursive order by base;
And i'm getting this error :
32044. 00000 - "cycle detected while executing recursive WITH query"
*Cause: A recursive WITH clause query produced a cycle and was stopped
in order to avoid an infinite loop.
*Action: Rewrite the recursive WITH query to stop the recursion or use
the CYCLE clause.
Where i'm wrong ?
I need to merge these two tables into one.
here's what I'd like to get as a result.
id code label id_parent
1 C1 LABEL_1
2 C2 LABEL_2
3 C3 LABEL_3
4 C4 LABEL_4
5 C5 LABEL_5
6 C1_1 LABEL_1_1 1
7 C1_2 LABEL_1_2 1
8 C1_3 LABEL_1_3 1
9 C1_4 LABEL_1_4 1
10 C3_1 LABEL_3_1 3
11 C3_2 LABEL_3_2 3
12 C3_3 LABEL_3_3 3
13 C3_4 LABEL_3_4 3
14 C5_1 LABEL_5_1 5
Thank you

Answer 1

Not sure why you want a recursive query? It appears that you could just use UNION ALL and join the two tables:
WITH table1 ( ID, Code, Label ) as(
SELECT 1, 'C1', 'LABEL_1' from dual UNION ALL
SELECT 2, 'C2', 'LABEL_2' from dual UNION ALL
SELECT 3, 'C3', 'LABEL_3' from dual UNION ALL
SELECT 4, 'C4', 'LABEL_4' from dual UNION ALL
SELECT 5, 'C5', 'LABEL_5' from dual
),
table2 ( ID, id_table1, code_child, label_child ) as (
SELECT 1, 1, 'C1_1','LABEL_1_1' from dual UNION ALL
SELECT 2, 1, 'C1_2','LABEL_1_2' from dual UNION ALL
SELECT 3, 1, 'C1_3','LABEL_1_3' from dual UNION ALL
SELECT 4, 1, 'C1_4','LABEL_1_4' from dual UNION ALL
SELECT 6, 3, 'C3_1','LABEL_3_1' from dual UNION ALL
SELECT 7, 3, 'C3_2','LABEL_3_2' from dual UNION ALL
SELECT 8, 3, 'C3_3','LABEL_3_3' from dual UNION ALL
SELECT 9, 3, 'C3_4','LABEL_3_4' from dual UNION ALL
SELECT 10, 5, 'C5_1','LABEL_5_1' from dual
)
SELECT ROW_NUMBER() OVER ( ORDER BY table_no, code ) AS id,
code,
label,
id_parent
FROM (
SELECT code,
label,
1 AS table_no,
NULL AS id_parent
FROM table1
UNION ALL
SELECT code_child,
label_child,
2 AS table_no,
id_table1
FROM table2
)
order by table_no, code;
Which outputs:
ID | CODE | LABEL | ID_PARENT
-: | :--- | :-------- | --------:
1 | C1 | LABEL_1 | null
2 | C2 | LABEL_2 | null
3 | C3 | LABEL_3 | null
4 | C4 | LABEL_4 | null
5 | C5 | LABEL_5 | null
6 | C1_1 | LABEL_1_1 | 1
7 | C1_2 | LABEL_1_2 | 1
8 | C1_3 | LABEL_1_3 | 1
9 | C1_4 | LABEL_1_4 | 1
10 | C3_1 | LABEL_3_1 | 3
11 | C3_2 | LABEL_3_2 | 3
12 | C3_3 | LABEL_3_3 | 3
13 | C3_4 | LABEL_3_4 | 3
14 | C5_1 | LABEL_5_1 | 5
db<>fiddle here

Answer 2

A recursive WITH clause query produced a cycle and was stopped in order to avoid an infinite loop.
This issue is coming due to bad data in the DB. There are some records which are causing circular relationship among them which is causing infinite loops.
For example: P is parent of C and C is again parent of P.
You can fetch the above output simple using UNION ALL and join of the tables.