SELECT (RETURN) N_Numbers_Of_Categories_Id From Categories_Table

How to ?

My Table : categories
Columns are
Id , int
name, varchar(255)
parent_id , int


Data is stored as
ID Name PARENT_ID
1 A 0
2 B 1
3 C 2
4 D 3
5 E 4


I want out put like

Column name ID
Values will be
1
2
3
4
5


HOW TO... Need Simple SQL Statement HERE!