I have three DropDownList, all have values of 1,2 and 3...

DropDownList1 has a selected value of 1

DropDownList2 has a selected value of 3

DropDownList3 has a selected value of 2


What I want is to swap values.

i.e. if I selected number 2 in DropDownList1, DropDownList3 should select 1 automatically.