Hierarchical table in Oracle - sql

Question

I have a problem with creating Hierarchical table, I searched a lot but this problem maybe different from the popular problem.
I have table that need to reconstruct
The input table :
| Agency_CODE | Code_length | Agency_Name
| 1 | 1 | Boogy
| 11 | 2 | Elhady
| 12 | 2 | EzzBatriq
| 13 | 2 | Haythomy
| 111 | 3 | Migz
| 121 | 3 | Mido
| 131 | 3 | Thabet
The hierarchy should be as : The agency which has only one digit is the root of the hierarchy 'Level 1', and level 2 the items which has two digits and level 3 which has 3 digits. Here we have 3 levels
So we need a query to get this output:
|Parent_ID |Parent_Name|Child_1_Id|Child_1_name|Child_2_Id|Child_2_name|
| 1 | Boogy | 11 | Elhady | 111 | Migz |
| 1 | Boogy | 12 | EzzBatriq | 121 | Mido |
| 1 | Boogy | 13 | Haythomy | 131 | Thabet |
Thanks in advance

Answer 1

SQL Fiddle
Oracle 11g R2 Schema Setup:
CREATE TABLE Agencies (
Agency_CODE NUMBER(8,0) CONSTRAINT Agencies__AC__PK PRIMARY KEY,
Code_length NUMBER(4,0) GENERATED ALWAYS AS ( LENGTH( Agency_Code ) ) VIRTUAL,
Agency_Name VARCHAR2(50),
parent_code NUMBER(7,0) GENERATED ALWAYS AS ( SUBSTR( Agency_Code, 1, LENGTH( Agency_Code ) - 1 ) ) VIRTUAL
CONSTRAINT Agencies__PC__FK REFERENCES Agencies( Agency_Code )
);
INSERT INTO Agencies ( Agency_CODE, Agency_Name )
SELECT 1, 'Boogy' FROM DUAL UNION ALL
SELECT 11, 'Elhady' FROM DUAL UNION ALL
SELECT 12, 'EzzBatriq' FROM DUAL UNION ALL
SELECT 13, 'Haythomy' FROM DUAL UNION ALL
SELECT 111, 'Migz' FROM DUAL UNION ALL
SELECT 121, 'Mido' FROM DUAL UNION ALL
SELECT 131, 'Thabet' FROM DUAL;
Query 1:
SELECT CONNECT_BY_ROOT( Agency_Code ) AS parent_id,
CONNECT_BY_ROOT( Agency_name ) AS parent,
PRIOR( Agency_Code ) AS child_id,
PRIOR( Agency_name ) AS child,
Agency_Code AS child2_id,
Agency_Name AS child2
FROM Agencies
WHERE LEVEL = 3
START WITH Code_length = 1
CONNECT BY PRIOR Agency_code = parent_code
Results:
| PARENT_ID | PARENT | CHILD_ID | CHILD | CHILD2_ID | CHILD2 |
|-----------|--------|----------|-----------|-----------|--------|
| 1 | Boogy | 11 | Elhady | 111 | Migz |
| 1 | Boogy | 12 | EzzBatriq | 121 | Mido |
| 1 | Boogy | 13 | Haythomy | 131 | Thabet |
Update: If you know the maximum depth of your nested hierarchy then you can use PIVOT:
SQL Fiddle
Oracle 11g R2 Schema Setup:
INSERT INTO Agencies ( Agency_CODE, Agency_Name )
SELECT 1311, 'Thabet.1' FROM DUAL;
Query 2:
SELECT *
FROM (
SELECT CONNECT_BY_ROOT( Agency_Code ) AS leaf_id,
Agency_Code,
code_length,
Agency_Name
FROM Agencies a
START WITH NOT EXISTS (
SELECT 1
FROM Agencies x
WHERE x.parent_code = a.agency_code
)
CONNECT BY PRIOR parent_code = Agency_code
) a
PIVOT(
MAX( agency_code ) AS id,
MAX( agency_name ) AS name
FOR code_length IN (
1 AS parent,
2 AS child,
3 AS child1,
4 AS child2
)
)
Results:
| LEAF_ID | PARENT_ID | PARENT_NAME | CHILD_ID | CHILD_NAME | CHILD1_ID | CHILD1_NAME | CHILD2_ID | CHILD2_NAME |
|---------|-----------|-------------|----------|------------|-----------|-------------|-----------|-------------|
| 121 | 1 | Boogy | 12 | EzzBatriq | 121 | Mido | (null) | (null) |
| 1311 | 1 | Boogy | 13 | Haythomy | 131 | Thabet | 1311 | Thabet.1 |
| 111 | 1 | Boogy | 11 | Elhady | 111 | Migz | (null) | (null) |