Populating 2nd Combo Box Dynamically On Making Selection From 1st Combobox

I m having three combo boxes on my asp page.
For 1st, i m fetching values thru a query.

For second, I want to populate it with values thru a query by giving the selection from first combobox as input.

Similarly for Third also i want to populate it with values using query by entering selection from second combobox as input.

So in other words second combobox is dependent on first and third combobox is dependent on second combobox.