postgresql - update tree table with rows from same table by changing id andparent_id

Question

I have 2 tables:

\\d folder

                              Table \"public.folder\"
Column   |         Type          |                             


        

Answer 1

CREATE OR REPLACE FUNCTION tree_copy(INTEGER,INTEGER) RETURNS VOID AS $$
DECLARE
    a ALIAS FOR $1; --ROOT FOLDER TO BE COPIED
    b ALIAS FOR $2; --DESTINATION FOLDER
    i INTEGER;
    j INTEGER;
    g INTEGER;
BEGIN
--DROP TABLE IF EXISTS temp1;

CREATE TEMPORARY TABLE temp1 AS(
WITH RECURSIVE CTE AS(
SELECT *, NEXTVAL('folder_id_seq') new_id FROM folder WHERE id = a
UNION ALL
SELECT folder.*,NEXTVAL('folder_id_seq') new_id FROM CTE
JOIN folder ON CTE.id = folder.parent_id)
SELECT C1.id, C1.new_id, C1.parent_id, 
C2.new_id new_parent_id FROM CTE C1 LEFT JOIN
CTE C2 ON C1.parent_id = C2.id);

FOR i IN (WITH RECURSIVE  t AS(SELECT id, parent_id FROM folder WHERE id = a
UNION SELECT f.id,f.parent_id FROM folder f, t AS t1 WHERE f.parent_id = t1.id)
SELECT id FROM t)
LOOP
    SELECT new_parent_id INTO g FROM temp1 WHERE id = i;

    INSERT INTO folder(id,name,parent_id)VALUES(
    (SELECT new_id FROM temp1 WHERE id = i),
    (SELECT name FROM folder WHERE id = i),COALESCE(g,b));

    FOR j IN (SELECT id FROM files WHERE folder_id = i)
    LOOP
        INSERT INTO files(id,name,folder_id) VALUES (
        NEXTVAL('files_id_seq'),(SELECT name FROM files WHERE id = j),
        (SELECT new_id FROM temp1 WHERE id = i));
    END LOOP;
END LOOP;
DROP TABLE temp1;
END;
$$ LANGUAGE PLPGSQL; 

this will do as i thought...

Answer 2

why do not use simple update ?

BEGIN;
UPDATE folder
SET    parent_id = 3
WHERE  id        = 5;

UPDATE files
SET    folder_id = 3
WHERE  folder_id = 5;
END;