how to link two dropdownlist in visual using csharp

you can also check it from

http://www.codeproject.com/Articles/38231/Simple-Way-to-Implement-Country-State-City-Dropdow
http://www.c-sharpcorner.com/uploadfile/rohatash/dropdownlist-with-country-state-and-city-in-asp-net/

hii

try any one of them

http://www.itorian.com/2013/02/cascading-dropdownlist-in-aspnet-mvc.html

or

follow given concept, but you need to write the codes..

lets assume first table is state and second is district --

you must need to relate both table by any one column(here is by state_id)

state table 

state_id statename
1           abc
2           def


districts table

districts_id  districts    state_id
1                 xyz                 1
2                hhh                 1
3                 kkkk                2


you can get districts  by following query



select districts from tbl_districts where state_id =(select state_id from tbl_state where statename=@statename)


you need to pass statename to @statename from first ddl.

and these data you need to store in datatable and bind it to second DDL