Doubts in dynamic binding of dropdownlist

[Saranya]

Hi friends

I m Saranya.In my coding there r 2 tables 1.category 2.designation

1.contains category id,category name

2.category id,designation id,designation name

in my interface there is a add button from where i added designation
details with category id fetched from category master.

in my bind i m showing all details from designation

my doubt is

i shud display category name in item template n in edititem template i
shud display a dropdownlist with items displaying from my database
category(category names list)

with the item selected.
the user can also change the category names listed in dropdown

how to achieve this?

plz help..............