Problem with derivation of tree-like structure by means of query

Question

Hi.
My name is Viktor. I'm from Russia so sorry for my English:)
You know I have the following problem:
Input data: For example, I have the following table with hierarchy (where ParentID is ID of the parent element in the same table, also we dont know the amount of levels in hierarchy previously).
Input table:
ID --------------Name----------- ParentID
1 ----------------Russia------------- Null
2 ----------Centr. Fed.Circle------ 1
3 -----------South.Fed.Circle------ 1
4 -----------Moscow region ---------2
5 --------------Podolsk ----------------4
Tell please how to receive the broach of that table with hierarchy by means of hierarchical query (or group of queries) to the following table:
Result table:
Attribute1------ Attribute2------------ Attribute3------------ Attribute4
Russia--------------Russia ----------------Russia------------------Russia
Russia -------Centr. Fed.Circle -----Moscow region --------Podolsk
Russia -------South.Fed.Circle ------South.Fed.Circle -----South.Fed.Circle
That is I need that the input table with the hierarchy would expand in the corresponding amount of columns in the result table (it depends on the amount of level in the input table) and would in due order, that is where we havenot value for level (for example we havenot values for the element Russia (first row in column Attribute1 in the result table in the following columns: Attribute2, Attribute3, Attribute4) we must fill these columns by the value from previous level.
I think you understood my task. If necessary i can give eхplanation more. Thanks for help.
Best regards, Viktor
Edited by: user8017496 on 10.02.2009 10:39
Edited by: user8017496 on 10.02.2009 10:52

Answer 1

Hi,
Below is a dynamic solution for SQL*Plus.
If you want to do this in PL/SQL, this should show you how.
--     *****  Start of dynamic_pivot.sql  *****
-- Suppress SQL*Plus features that interfere with raw output
SET     FEEDBACK     OFF
SET     PAGESIZE     0
-- Preliminary query to write 2nd, 3rd, ... SELECT columns
SPOOL     p:\sql\cookbook\dynamic_pivot_subscript.sql
WITH     got_path     AS
     SELECT     LEVEL                     AS lvl
     FROM     input_table
     START WITH     parentid     IS NULL
     CONNECT BY     parentid     = PRIOR id
SELECT     ',     MAX (NVL (REGEXP_SUBSTR (path, ''[^/]+'', 1, '
     ||      TO_CHAR (LEVEL + 1)
     ||     '), name))     AS attribute'
     ||      TO_CHAR (LEVEL + 1)
FROM     dual
CONNECT BY     LEVEL     <     (
                    SELECT     MAX (lvl)
                    FROM     got_path
SPOOL     OFF
-- Restore SQL*Plus features suppressed earlier
SET     FEEDBACK     ON
SET     PAGESIZE     50
-- Main Query
WITH     got_path     AS
     SELECT     name
     ,     LEVEL                    AS lvl
     ,     SYS_CONNECT_BY_PATH (name, '/')     AS path
     FROM     input_table
     START WITH     parentid     IS NULL
     CONNECT BY     parentid     = PRIOR id
,     cntr     AS
     SELECT     LEVEL     AS n
     FROM     dual
     CONNECT BY     LEVEL     <=     (
                         SELECT     MAX (lvl)
                         FROM     got_path
SELECT     MAX (NVL (REGEXP_SUBSTR (path, '[^/]+', 1, 1), name))     AS attribute1
@p:\sql\cookbook\dynamic_pivot_subscript.sql
FROM     got_path
JOIN     cntr          ON n     <= lvl
GROUP BY     name;When I used the dynamic_pivot_subscript.sql on the folder p:\sql\cookbook, you can use any file on any folder available from your SQL*Plus client machine.
I'm not saying that there's anything wrong with 3 rows of output. I'm only saying that I don't understand why you want 3 rows, and why you want those 3 rows. If I understood the problem, then I could probably show you a solution.
I don't mind explaining things that you don't understand, but I don't want to waste time explaining things that you already do understand.
Fell free to ask specific questions.