Convert the below logic in oracle tree - sql

Question

Recursively the parent is inserted first and then the children. How can I migrate the logic in Oracle using parent-child.The logic for the SQL should be first the parent is evaluated and then inserted or added and then the child is checked and then it is prepared.
Thank you for the response , the table structure as follow Name
REF_ID NOT NULL NUMBER
REF_TYPE_ID NOT NULL NUMBER
PARENT_REF_ID NUMBER
REF_VALUE NOT NULL VARCHAR2(255)
Now the expected result conditions: we need to start finding the query with ref_id, so if ref_id is supposed 14, then we need to check the corresponding should have parent_ref_id is null or not, if parent_ref_id is present suppose 4, then we need to again get the value for 4 as ref_id and check is parent_id is null or not If null then we need to check the value ref_type_id whether it is 1, 2,3,4,..; etc and based on the condition we need to append the result 4(parent_ref_id) with some text let it be 'article 4'. Now resuming back to the loop, the user had enter ref_id 14, then we need to check the value for ref_type_id for the corresponding and then we need to append with the result suppose 'par 14' and this result had to come after parent result: article 4 par 14 (article 4 - parent, par 14 children)

Answer 1

I believe that using a CONNECT BY statement with SYS_CONNECT_BY_PATH should be able to help you achieve your goal.
WITH
refs (ref_id,
ref_type_id,
parent_ref_id,
ref_value)
AS
(SELECT 501, 1, NULL, 207 FROM DUAL
UNION ALL
SELECT 502, 2, 501, 4 FROM DUAL
UNION ALL
SELECT 503, 3, 502, 1 FROM DUAL)
SELECT CONNECT_BY_ROOT r.ref_id as starting_ref_id,
TRIM (
',' FROM
SYS_CONNECT_BY_PATH (
CASE r.ref_type_id
WHEN 1 THEN 'article '
WHEN 2 THEN 'par '
WHEN 3 THEN '('
WHEN 4 THEN 'point '
WHEN 5 THEN 'sous '
WHEN 6 THEN NULL
WHEN 8 THEN NULL
ELSE '/'
END
|| r.ref_id,
',')) AS ref_label
FROM refs r
WHERE CONNECT_BY_ISLEAF = 1
CONNECT BY PRIOR r.parent_ref_id = r.ref_id;
STARTING_REF_ID REF_LABEL
__________________ ___________________________
501 article 501
502 par 502,article 501
503 (503,par 502,article 501