Hierarchical + Analytical query for organizational unit parameters

Question

Hello gurus,
I try for a couples of hour ago to make a query work as I would like.
Our application need to store some parameters for our organization units. These organization units are typically organized in in an hierarchy manner: one top unit with many level of child units. The parameters are stored into another table with 1:1 relationship.
For sake of visualisation, here is the data for the organization unit and parameter table in a more visual format:
SQL> select * from organization_unit;
UNIT_CODE  UNIT_NAME            PARENT_UNIT_CODE
00000      Top level
10         L2 unit #10          00000
10-01      L3 unit #10-01       10
10-02      L3 unit #10-02       10
20         L2 unit #20          00000
20-01      L3 unit #20-01       20
20-02      L3 unit #20-02       20
SQL>  select * from org_unit_parameters;
UNIT_CODE  PARAM1               PARAM2               PARAM3               PARAM4
00000      Default value        Default value        Default value        {null}
10         {null}               Value from 10        Value from 10        {null}
10-01      {null}               {null}               Value from 10-01     {null}
10-02      {null}               {null}               {null}               Value from 10-02
20         Value from 20        Value from 20        Value from 20        {null}
20-01      {null}               Value from 20-01     {null}               {null}
20-02      {null}               Value from 20-02     {null}               {null}The application will query the parameter table to get a parameter value for a given unit.
The parameter resolution algorithm is rather simple: when querying a unit, the applicable parameter is the one defined at the requested level. If the parameter is not defined (null) at the requested level, the parameter value that must be returned is the next defined one in the parent hierarchy. In some rare cases, it can be null if a parameter is not defined anywhere from the requested level to top.
I've made a query that seems to work when querying for one unit at a time. It use hierarchical operators (start with + connect by) with a bit of analytical functions. Here is a test & raw output example:
SQL> WITH hierarchy
  2  AS
  3  (
  4    SELECT ou.unit_code,
  5         LEVEL            AS lvl
  6    FROM   organization_unit ou
  7    START WITH
  8      ou.unit_code = '20-01'
  9    CONNECT BY
10      ou.unit_code = PRIOR ou.parent_unit_code
11  )
12  SELECT h.*,
13       p.param1                                                        AS param1_raw,
14       LAST_VALUE (p.param1 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param1_with_last,
15       FIRST_VALUE(p.param1 IGNORE NULLS) OVER (ORDER BY h.lvl ASC)    AS param1_with_first,
16       p.param2                                                        AS param2_raw,
17       LAST_VALUE (p.param2 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param2_with_last,
18       FIRST_VALUE(p.param2 IGNORE NULLS) OVER (ORDER BY h.lvl ASC)    AS param2_with_first,
19       p.param3                                                        AS param3_raw,
20       LAST_VALUE (p.param3 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param3_with_last,
21       FIRST_VALUE(p.param3 IGNORE NULLS) OVER (ORDER BY h.lvl ASC)    AS param3_with_first,
22       p.param4                                                        AS param4_raw,
23       LAST_VALUE (p.param4 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param4_with_last,
24       FIRST_VALUE(p.param4 IGNORE NULLS) OVER (ORDER BY h.lvl ASC)    AS param4_with_first
25  FROM   hierarchy                                h
26         LEFT JOIN org_unit_parameters         p
27         ON h.unit_code = p.unit_code
28  ORDER BY h.lvl DESC;
UNIT_CODE   LVL PARAM1_RAW           PARAM1_WITH_LAST     PARAM1_WITH_FIRST    PARAM2_RAW           PARAM2_WITH_LAST     PARAM2_WITH_FIRST    PARAM3_RAW           PARAM3_WITH_LAST     PARAM3_WITH_FIRST    PARAM4_RAW           PARAM4_WITH_LAST     PARAM4_WITH_FIRST
00000         3 Default value        Default value        Value from 20        Default value        Default value        Value from 20-01     Default value        Default value        Value from 20        {null}               {null}               {null}
20            2 Value from 20        Value from 20        Value from 20        Value from 20        Value from 20        Value from 20-01     Value from 20        Value from 20        Value from 20        {null}               {null}               {null}
20-01         1 {null}               Value from 20        {null}               Value from 20-01     Value from 20-01     Value from 20-01     {null}               Value from 20        {null}               {null}               {null}               {null}Seems pretty good, the upper parameters are well «propagated» down with LAST_VALUE function. But, I don't understand why the use of FIRST_VALUE and oppposite ordering doesn't give the same result. A little more playing with the last query for getting the final result for a given unit code:
SQL> SELECT *
  2  FROM
  3  (
  4     WITH hierarchy
  5     AS
  6     (
  7        SELECT ou.unit_code,
  8               LEVEL            AS lvl
  9        FROM   organization_unit ou
10        START WITH
11           ou.unit_code = '20-01'
12        CONNECT BY
13           ou.unit_code = PRIOR ou.parent_unit_code
14     )
15     SELECT h.*,
16            LAST_VALUE (p.param1 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param1,
17            LAST_VALUE (p.param2 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param2,
18            LAST_VALUE (p.param3 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param3,
19            LAST_VALUE (p.param4 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param4
20     FROM   hierarchy                                h
21               LEFT JOIN org_unit_parameters         p
22               ON h.unit_code = p.unit_code
23     ORDER BY h.lvl
24  )
25  WHERE ROWNUM = 1;
UNIT_CODE   LVL PARAM1               PARAM2               PARAM3               PARAM4
20-01         1 Value from 20        Value from 20-01     Value from 20        {null}Works well!
But, my ultimate goal is to create a view that resolve correctly all these parameters for each level of the organization with proper propagation rather then querying for each unit at a time. I played a bit, but without success. :( My current raw query is this one:
SQL> WITH hierarchy
  2  AS
  3  (
  4     SELECT ou.unit_code,
  5            LPAD(' ',2*(LEVEL-1)) || ou.unit_code    AS tree,
  6            LEVEL                                    AS lvl
  7     FROM   organization_unit ou
  8     START WITH
  9        parent_unit_code IS NULL
10     CONNECT BY
11        PRIOR unit_code =  parent_unit_code
12  )
13  SELECT h.*,
14         p.param1                                                        AS param1_raw,
15         LAST_VALUE (p.param1 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param1_with_last,
16         FIRST_VALUE(p.param1 IGNORE NULLS) OVER (ORDER BY h.lvl ASC)    AS param1_with_first,
17         p.param2                                                        AS param2_raw,
18         LAST_VALUE (p.param2 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param2_with_last,
19         FIRST_VALUE(p.param2 IGNORE NULLS) OVER (ORDER BY h.lvl ASC)    AS param2_with_first,
20         p.param3                                                        AS param3_raw,
21         LAST_VALUE (p.param3 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param3_with_last,
22         FIRST_VALUE(p.param3 IGNORE NULLS) OVER (ORDER BY h.lvl ASC)    AS param3_with_first,
23         p.param4                                                        AS param4_raw,
24         LAST_VALUE (p.param4 IGNORE NULLS) OVER (ORDER BY h.lvl DESC)   AS param4_with_last,
25         FIRST_VALUE(p.param4 IGNORE NULLS) OVER (ORDER BY h.lvl ASC)    AS param4_with_first
26  FROM   hierarchy                          h
27            LEFT JOIN org_unit_parameters   p
28            ON h.unit_code = p.unit_code
29  ORDER BY h.unit_code;
UNIT_CODE  TREE        LVL PARAM1_RAW                PARAM1_WITH_LAST          PARAM1_WITH_FIRST      PARAM2_RAW                   PARAM2_WITH_LAST          PARAM2_WITH_FIRST         PARAM3_RAW                PARAM3_WITH_LAST          PARAM3_WITH_FIRST         PARAM4_RAW                PARAM4_WITH_LAST       PARAM4_WITH_FIRST
00000      00000         1 Default value             Default value             Default value          Default value                Default value             Default value             Default value             Default value             Default value             {null}                    Value from 10-02       {null}
10           10          2 {null}                    Value from 20             Default value          Value from 10                Value from 10             Default value             Value from 10             Value from 10             Default value             {null}                    Value from 10-02       {null}
10-01          10-01     3 {null}                    {null}                    Default value          {null}                       Value from 20-02          Default value             Value from 10-01          Value from 10-01          Default value             {null}                    Value from 10-02       Value from 10-02
10-02          10-02     3 {null}                    {null}                    Default value          {null}                       Value from 20-02          Default value             {null}                    Value from 10-01          Default value             Value from 10-02          Value from 10-02       Value from 10-02
20           20          2 Value from 20             Value from 20             Default value          Value from 20                Value from 10             Default value             Value from 20             Value from 10             Default value             {null}                    Value from 10-02       {null}
20-01          20-01     3 {null}                    {null}                    Default value          Value from 20-01             Value from 20-02          Default value             {null}                    Value from 10-01          Default value             {null}                    Value from 10-02       Value from 10-02
20-02          20-02     3 {null}                    {null}                    Default value          Value from 20-02             Value from 20-02          Default value             {null}                    Value from 10-01          Default value             {null}                    Value from 10-02       Value from 10-02As you can see, it's not as I expected. I know there's something to do with a PARTITION BY clause, but don't know how.
Is anyone knows how to solve my problem?
Thanks
Bruno
For reproductibility purposes, here is the code to create sturcture and data:
Here is the format of my tables and some samble data:
CREATE TABLE organization_unit (
   unit_code         VARCHAR2(5 CHAR)   NOT NULL PRIMARY KEY,
   unit_name         VARCHAR2(100 CHAR) NOT NULL,
   parent_unit_code  VARCHAR2(5 CHAR)  
CREATE TABLE org_unit_parameters (
   unit_code         VARCHAR2(5 CHAR)   NOT NULL PRIMARY KEY,
   param1            VARCHAR2(100 CHAR),
   param2            VARCHAR2(100 CHAR),
   param3            VARCHAR2(100 CHAR),
   param4            VARCHAR2(100 CHAR)
-- Inserting data
INSERT INTO organization_unit (unit_code, unit_name, parent_unit_code)
VALUES ('00000', 'Top level', NULL);
INSERT INTO organization_unit (unit_code, unit_name, parent_unit_code)
VALUES ('10', 'L2 unit #10', '00000');
INSERT INTO organization_unit (unit_code, unit_name, parent_unit_code)
VALUES ('10-01', 'L3 unit #10-01', '10');
INSERT INTO organization_unit (unit_code, unit_name, parent_unit_code)
VALUES ('10-02', 'L3 unit #10-02', '10');
INSERT INTO organization_unit (unit_code, unit_name, parent_unit_code)
VALUES ('20', 'L2 unit #20', '00000');
INSERT INTO organization_unit (unit_code, unit_name, parent_unit_code)
VALUES ('20-01', 'L3 unit #20-01', '20');
INSERT INTO organization_unit (unit_code, unit_name, parent_unit_code)
VALUES ('20-02', 'L3 unit #20-02', '20');
INSERT INTO ORG_UNIT_PARAMETERS (unit_code, param1, param2, param3)
VALUES ('00000', 'Default value', 'Default value', 'Default value');
INSERT INTO ORG_UNIT_PARAMETERS (unit_code, param2, param3)
VALUES ('10', 'Value from 10', 'Value from 10');
INSERT INTO ORG_UNIT_PARAMETERS (unit_code, param3)
VALUES ('10-01', 'Value from 10-01');
INSERT INTO ORG_UNIT_PARAMETERS (unit_code, param4)
VALUES ('10-02', 'Value from 10-02');
INSERT INTO ORG_UNIT_PARAMETERS (unit_code, param1, param2, param3)
VALUES ('20', 'Value from 20', 'Value from 20', 'Value from 20');
INSERT INTO ORG_UNIT_PARAMETERS (unit_code, param2)
VALUES ('20-01', 'Value from 20-01');
INSERT INTO ORG_UNIT_PARAMETERS (unit_code, param2)
VALUES ('20-02', 'Value from 20-02');
COMMIT;

Answer 1

Now, I hoppe I got your reqs:
WITH hierarchy AS (
                   SELECT  ou.unit_code,
                           LPAD(' ',2*(LEVEL-1)) || ou.unit_code    AS tree,
                           LEVEL                                    AS lvl,
                           param1                                   AS param1_raw,
                           param2                                   AS param2_raw,
                           param3                                   AS param3_raw,
                           param4                                   AS param4_raw,
                           SYS_CONNECT_BY_PATH(p.param1,'#') || '#' AS param1_path,
                           SYS_CONNECT_BY_PATH(p.param2,'#') || '#' AS param2_path,
                           SYS_CONNECT_BY_PATH(p.param3,'#') || '#' AS param3_path,
                           SYS_CONNECT_BY_PATH(p.param4,'#') || '#' AS param4_path
                     FROM  organization_unit ou LEFT JOIN org_unit_parameters p
                             ON ou.unit_code = p.unit_code
                     START WITH parent_unit_code IS NULL
                     CONNECT BY PRIOR ou.unit_code =  parent_unit_code
SELECT  unit_code,
        tree,
        lvl,
        param1_raw,
        REGEXP_SUBSTR(param1_path,'[^#]+',1,GREATEST(1,REGEXP_COUNT(param1_path,'[^#]+'))) AS param1_with_last,
        REGEXP_SUBSTR(param1_path,'[^#]+')                                                 AS param1_with_first,
        param2_raw,
        REGEXP_SUBSTR(param2_path,'[^#]+',1,GREATEST(1,REGEXP_COUNT(param2_path,'[^#]+'))) AS param2_with_last,
        REGEXP_SUBSTR(param2_path,'[^#]+')                                                 AS param2_with_first,
        param3_raw,
        REGEXP_SUBSTR(param3_path,'[^#]+',1,GREATEST(1,REGEXP_COUNT(param3_path,'[^#]+'))) AS param3_with_last,
        REGEXP_SUBSTR(param3_path,'[^#]+')                                                 AS param3_with_first,
        param4_raw,
        REGEXP_SUBSTR(param4_path,'[^#]+',1,GREATEST(1,REGEXP_COUNT(param4_path,'[^#]+'))) AS param4_with_last,
        REGEXP_SUBSTR(param4_path,'[^#]+')                                                 AS param4_with_first
  FROM  hierarchy
  ORDER BY unit_code
UNIT_ TREE              LVL PARAM1_RAW       PARAM1_WITH_LAST PARAM1_WITH_FIRS PARAM2_RAW       PARAM2_WITH_LAST PARAM2_WITH_FIRS PARAM3_RAW       PARAM3_WITH_LAST PARAM3_WITH_FIRS PARAM4_RAW       PARAM4_WITH_LAST PARAM4_WITH_FIRS
00000 00000               1 Default value    Default value    Default value    Default value    Default value    Default value    Default value    Default value    Default value
10      10                2                  Default value    Default value    Value from 10    Value from 10    Default value    Value from 10    Value from 10    Default value
10-01     10-01           3                  Default value    Default value                     Value from 10    Default value    Value from 10-01 Value from 10-01 Default value
10-02     10-02           3                  Default value    Default value                     Value from 10    Default value                     Value from 10    Default value    Value from 10-02 Value from 10-02 Value from 10-02
20      20                2 Value from 20    Value from 20    Default value    Value from 20    Value from 20    Default value    Value from 20    Value from 20    Default value
20-01     20-01           3                  Value from 20    Default value    Value from 20-01 Value from 20-01 Default value                     Value from 20    Default value
20-02     20-02           3                  Value from 20    Default value    Value from 20-02 Value from 20-02 Default value                     Value from 20    Default value
7 rows selected.
SQL>  SY.
Edited by: Solomon Yakobson on Nov 12, 2010 10:09 AM