How to store, data of hierarchical in nature?

Question

Hi,
We are designing a database for our office. Part of our data is
hierarchical in nature, and I am not sure how to store that data in relational tables.
we have many training courses, each belongs to many groups, sub-groups. Depth of this tree is not pre-determined and it may grow to maximum five to six levels.
For Example:
1. Consider five training courses A,B,C,D,E
2. A,B,C belongs to Group G1 and D,E belongs to Group G2
3. Group G1, G2 are part of Group GG1
4. and this grouping is dynamic in nature.
Is there any standard way to store this kind of group information
in relational model.
natrajv
mumbai

Answer 1

CREATE TABLE O_GROUP
(id number,
name varchar2(100),
father_id number,
constraint pk_o_group primary key(id),
constraint fk_o_group foreign key(father_id)
references o_group(id))
-- father_id builds a hierarchical tree
CREATE TABLE O_COURSE
(id number,
name varchar2(100),
o_group_id number,
constraint pk_o_course primary key(id),
constraint fk_o_course_grp foreign Key(o_group_id)
references O_GROUP(id))
insert into 0_GROUP
values(1,'GG1',NULL);
insert into O_GROUP
values(2,'G1',1);
insert into O_GROUP
values(3,'G2',1);
insert into O_COURSE
values(1,'A',2);
insert into O_COURSE
values(2,'B',2);
insert into O_COURSE
values(3,'C',2);
insert into O_COURSE
values(4,'D',3);
insert into O_COURSE
values(5,'E',3);
commit;