Question

I have 2 tables:

\d folder

                              Table "public.folder"
Column   |         Type          |                      Modifiers                      
---------+-----------------------+----------------------------------------------------
id        | integer               | not null default nextval('folder_id_seq'::regclass)
name      | character varying(20) | 
parent_id | integer               | 

Indexes:
  "folder_pkey" PRIMARY KEY, btree (id)

Foreign-key constraints:
  "fk_folder_1" FOREIGN KEY (parent_id) REFERENCES folder(id)

Referenced by:
  TABLE "files" CONSTRAINT "fk_files_1" FOREIGN KEY (folder_id) REFERENCES folder(id)
  TABLE "folder" CONSTRAINT "fk_folder_1" FOREIGN KEY (parent_id) REFERENCES folder(id)

\d files

                              Table "public.files"
Column    |         Type          |                     Modifiers                      
----------+-----------------------+---------------------------------------------------
id        | integer               | not null default nextval('files_id_seq'::regclass)
name      | character varying(20) | 
folder_id | integer               | 

Indexes:
  "files_pkey" PRIMARY KEY, btree (id)

Foreign-key constraints:
  "fk_files_1" FOREIGN KEY (folder_id) REFERENCES folder(id)


select * from folder;
 id |  name   | parent_id 
----+---------+-----------
  1 | home    |          
  2 | folder2 |         1
  3 | folder3 |         1
  4 | folder4 |         2
  5 | folder5 |         4
  6 | folder6 |         5

(6 rows)



select * from files;
 id | name  | folder_id 
----+-------+-----------
  1 | file1 |         4
  2 | file2 |         4
  3 | file3 |         5
  4 | file4 |         6
  5 | file5 |         6
  6 | file6 |         2
(6 rows)

Now I need a function or cursor or any thing which will get two inputs,folder to copy and destination folder to copy, the function should copy the folder and its child folders into the same table with new id and parent id as below, same time when folder is copied and inserted the file in files table is also to be inserted, plz help me get the below result..

if I am coping folder5 to folder3 my output should be like this:

select * from folder;
 id |  name   | parent_id 
----+---------+-----------
  1 | home    |          
  2 | folder2 |         1
  3 | folder3 |         1
  4 | folder4 |         2
  5 | folder5 |         4
  6 | folder6 |         5
  7 | folder5 |         3
  8 | folder6 |         7
(8 rows)

and files table is also to be updated when folder is copied and inserted like this:

 select * from files;
 id | name  | folder_id 
----+-------+-----------
  1 | file1 |         4
  2 | file2 |         4
  3 | file3 |         5
  4 | file4 |         6
  5 | file5 |         6
  6 | file6 |         2
  7 | file3 |         7
  8 | file4 |         8
  9 | file5 |         8
(9 rows)

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…