Add text in dropdownlist

Hi Guys,

I created 2dropdownlists and bind them. First dropdown is ID and second dropdown  is Name. Here ID  is auto increment. Now my problem is when i want try to add something in second dropdown it doesn't allow me to type. how to add text in second dropdownlist and first dropdownlist clear the items and it should be selected.(can't edit) can any one help? I am doing in asp.net

 

Thanks
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