I want to populate a combo that based on another combo.
For example, If i select country from the first combo, the second combo automatically fills with its cities.
Please if anybody can write the code ...

You could have a db with 2 tables - one is countries, the other is cities.

In the cities table - have a column 'country' that references the countries table.

On your web page, pull countries from the db, and cities for that country to populate your 2 drop down menu's

Using javascript - onChange the country selector - reload the page with the value of the country sent in a query.

It should be really easy to do it - assuming you have some asp / sql / js knowledge.

Perhaps this may hopefully give you some ideas. It's got a downloadable sample and does retain values after the post back:

Classic ASP Design Tips - Dependent Listboxes
http://www.bullschmidt.com/devtip-de...tlistboxes.asp