How To Get Entire Linked Group Details using SQL?

In have table called "MYGROUP" in database. I display this table data in tree format in GUI as below:

Vishal Group
|
|-------Vishal Group1
|          |-------Vishal Group1.1
|                     |-------Vishal Group1.1.1
|
|-------Vishal Group2
|          |-------Vishal Group2.1
|                     |-------Vishal Group2.1.1
|
|-------Vishal Group3
|   
|-------Vishal Group4
|          |-------Vishal Group4.1

Actually, the requirement is, I need to visit the lowest root for every group, if that respective group is not used in other specific tables then I would delete that record from respective table.

I need to get all the details only for the main group called "Vishal Group", please refer to both snaps, one contains entire table data and the other snap (snap which has tree format details)shows expected data i.e. I need to get only those records as a result of a SQL execution.

I tried with self join (generally we do for MGR and Employee column relationship), but no success to get the records which falls under "Vishal Group" which is the base of all records.

I have added a table DDL and Insert SQL for reference as below. And also attached a snap of how data looks in the table.

CREATE TABLE MYGROUP 
(
  PK_GROUP GUID DEFAULT 'newid()' NOT NULL,
  DESCRIPTION Varchar(255),
  LINKED_TO_GROUP GUID,
  PRIMARY KEY (PK_GROUP)
);

COMMIT;


INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{11111111-111-1111-1111-111111111111} ', 'My Items', NULL);


INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{CD1E33D1-1666-49B9-83BE-067687E4DDD6}', 'Vishal Group', '{11111111-111-1111-1111-111111111111}');

INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{4B42E7A5-B14C-451B-ACF5-83DD8A983A58}', 'Vishal Group1', '{CD1E33D1-1666-49B9-83BE-067687E4DDD6}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{A87E921D-0468-497D-92C5-19AB63751EE8}', 'Vishal Group1.1', '{4B42E7A5-B14C-451B-ACF5-83DD8A983A58}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{0FDC729A-8FCC-4D23-8619-436A459835DD}', 'Vishal Group1.1.1', '{A87E921D-0468-497D-92C5-19AB63751EE8}');

INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{2E15A2A9-7E40-422E-A5D6-C3F6C63F8591}', 'Vishal Group2', '{CD1E33D1-1666-49B9-83BE-067687E4DDD6}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{5EAC9866-F406-4BBD-B7B3-5CEEC3877C9B}', 'Vishal Group2.1', '{2E15A2A9-7E40-422E-A5D6-C3F6C63F8591}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{A326E6E3-030E-493B-AA0E-DC5D90DB080F}', 'Vishal Group2.1.1', '{5EAC9866-F406-4BBD-B7B3-5CEEC3877C9B}');

INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{3CF1FE37-EEC0-4E79-A3C5-DB78F6A9BC05}', 'Vishal Group3', '{CD1E33D1-1666-49B9-83BE-067687E4DDD6}');

INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{1EC302C8-0AB3-4F67-B47A-CC43401DF4ED}', 'Vishal Group4', '{CD1E33D1-1666-49B9-83BE-067687E4DDD6}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{2EB81764-04FA-4DDA-9AAB-A607BDC2756D}', 'Vishal Group4.1', '{1EC302C8-0AB3-4F67-B47A-CC43401DF4ED}');


INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{7D939081-13F0-404C-9F2F-5222C628FDCC}', 'Sample BOMs', '{11111111-111-1111-1111-111111111111}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{C77D2255-AC47-461D-BEE5-7F3154C23AF1}', 'Test1', '{11111111-111-1111-1111-111111111111}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{D054539A-BBBA-4E3F-9746-1522FF8A1E89}', 'Test2', '{11111111-111-1111-1111-111111111111}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{71B4751C-7096-4FB9-8D71-6BB19A3D9ED9}', 'Trailer Assy', '{11111111-111-1111-1111-111111111111}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{F702BABB-73B0-4A49-B442-1C7C8A126335}', 'WIP', '{11111111-111-1111-1111-111111111111}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{FC74D59A-94E3-4209-BCEA-1B7606EA62F1}', 'mmmmmm', '{11111111-111-1111-1111-111111111111}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{6E4354F9-B298-4737-9C18-51B4ACAC0734}', 'test1', '{11111111-111-1111-1111-111111111111}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{42A48EE0-D4EE-4828-BC11-D7F0D1FE5BEC}', 'test1', '{11111111-111-1111-1111-111111111111}');
INSERT INTO MYGROUP (PK_GROUP, DESCRIPTION, LINKED_TO_GROUP) VALUES ('{28AFE8E1-1221-4F94-BAE3-37EA6B360494}', 'test_2', '{11111111-111-1111-1111-111111111111}');

COMMIT;

Any idea how to get records which falls under "Vishal Group" ?

You can use recursive stored procedure like this :

  SET TERM ^ ;    

  create or alter procedure MYGROUP_PROC (
        IPARENT varchar(64))
    returns (
        PK_GROUP varchar(64),
        DESCRIPTION varchar(255),
        LINKED_TO_GROUP varchar(64))
    as
    declare variable I integer;
    BEGIN
      FOR
        select 
            mygroup.pk_group,
            mygroup.description,
            mygroup.linked_to_group
        from mygroup
        where
          (upper(mygroup.linked_to_group) = upper(:iparent))
        INTO :PK_GROUP,
             :DESCRIPTION,
             :LINKED_TO_GROUP
      DO
      BEGIN
        suspend;
        i = 0;
        /* Stored procedures can be nested up to 1,000 levels deep. This limitation helps to prevent infinite loops that can occur when a recursive procedure provides no absolute terminating condition.*/
        while (i < 1000) do
          begin
            execute procedure mygroup_proc(:pk_group) returning_values (:pk_group,:description,:linked_to_group);
            if (:pk_group is null) then break;
            suspend;
            i = i+1;
          end
      END
    END^

SET TERM ; ^ 

When input parameter is {CD1E33D1-1666-49B9-83BE-067687E4DDD6} (PK of Vishal Group

) the result is :

Update

Is it possible to get "Vishal Group" record also in the output ?

Yes, first reading you can execute procedure above in other procedure like:

SET TERM ^ ;

create or alter procedure MYGROUP_PROC_1 (
    IPARENT varchar(100))
returns (
    PK_GROUP varchar(64),
    DESCRIPTION varchar(255),
    LINKED_TO_GROUP varchar(64))
as
BEGIN
  FOR
    select 
        mygroup.pk_group,
        mygroup.description,
        mygroup.linked_to_group
    from mygroup
    where 
      (upper(mygroup.description) = upper(:iparent))
      /*
      or (upper(mygroup.pk_group) = upper(:iparent)) instead
      if you want to use pk_group as input parameter
      */
    INTO :PK_GROUP,
         :DESCRIPTION,
         :LINKED_TO_GROUP
  DO
  BEGIN
    suspend;
     for
      select pk_group, description,linked_to_group from mygroup_proc(:pk_group)
      into
        :PK_GROUP,
        :DESCRIPTION,
        :LINKED_TO_GROUP
    do
      begin
        suspend;
      end
  end
END^ 

SET TERM ; ^ 

Then use

SELECT * FROM MYGROUP_PROC_1('Vishal Group')

or

SELECT * FROM MYGROUP_PROC_1('{CD1E33D1-1666-49B9-83BE-067687E4DDD6}')

if you use pk_group as parameter