Categories and Sub Categories (Nested)

Hi,

I have a postgresql database Table Categories which has the structure like
this

Cat_ID | Parent_ID | Name
------------------------------------
1 | 0 | Automobiles
2 | 0 | Beauty & Health
3 | 1 | Bikes
4 | 1 | Cars
5 | 3 | Suzuki
6 | 3 | Yamaha
7 | 0 | Clothes

According to the above Database data, Suzuki and Yamaha are the
Subcategories of Category Bikes and Bikes in turn is the Subcategory of
Automobiles.

My question is what is the advantage of Creating NESTED Table over have a
table structure below which achieve the same goal:

>>Category Table

Cat_ID | Cat_Name
------------------------------------
1 | Automobiles
2 | Beauty & Health
3 | Bikes
4 | Cars
7 | Clothes

>>Subcategory Table

Subcat_ID | Sub_Cat_ID | Sub_Name
------------------------------------------------------
10 | 3 | Suzuki
11 | 3 | Yamaha
12 | 1 | Bikes
13 | 1 | Cars

Since all display the data in them in a tree structure like below

Automobiles
---> Bikes
------> Suzuki
------> Yamaha
---> Cars
Beauty & Health
Clothes

Please advice should I Create a Nested Table Categories or
Should I create TWO Tables, Category Table and Subcategory Table?

Thanks once again.
+-----------------------------------------------------+
| Martin W. Kuria (Mr.) martin.kuria@unon.org
+----------------------------------------------------+

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