I have a parent-child relationship in an Oracle 9i database-table
like:
parent | child
1 | 2
2 | 3
2 | 4
null | 1
1 | 8
I need to get the absolute parent from a given child. Say, I have child 4, it has to give me parent: 1
I already looked to CONNECT BY , but I can't find the solution.
you could use a CONNECT BY query to build the list of parents and then filter :
SQL> WITH tree AS (
2 SELECT 1 parent_id, 2 child_id FROM DUAL
3 UNION ALL SELECT 2 , 3 FROM DUAL
4 UNION ALL SELECT 2 , 4 FROM DUAL
5 UNION ALL SELECT null, 1 FROM DUAL
6 UNION ALL SELECT 1 , 8 FROM DUAL
7 )
8 SELECT child_id
9 FROM (SELECT *
10 FROM tree
11 CONNECT BY PRIOR parent_id = child_id
12 START WITH child_id = 4)
13 WHERE parent_id IS NULL;
CHILD_ID
----------
1
SELECT parent
FROM (
SELECT parent
FROM (
SELECT parent, level AS l
FROM mytable
START WITH
child = 4
CONNECT BY
child = PRIOR parent
)
ORDER BY
l DESC
)
WHERE rownum = 1
This will give you NULL as the absolute parent.
If you want 1, replace parent with child:
SELECT child
FROM (
SELECT child
FROM (
SELECT child, level AS l
FROM mytable
START WITH
child = 4
CONNECT BY
child = PRIOR parent
)
ORDER BY
l DESC
)
WHERE rownum = 1
