listbox selection with in DropdownList in asp.Net ?.

Question

 Hi Friends ,

 

            I want  to have listbox items within the dropdownList in asp.net. The Items within dropdown which comes from database .When i select the dropdown list values , i must have multiple select option in it. If anyone knows it , give me suggestion with example code.

 

 

Thanks in Advance ,

 

Karthik K