I am doubt your question is regarding Crystal Report or the form combo box logic?
your combo box should work as cascade combobox.
first fill the item to the company combo box
cbCompany
. then load the city combo when the user select a company. you can load the city combo with cbCompany SelectedIndexChanged event.
you have to modify the City combo stored procedure as
string selectedCompany= cbCompany.SelectedValue;
cm = New SqlCommand("Select distinct City From Staff Where Company='" + selectedCompany + "'", cn)
I'm not much familer with VB.net coding. may be syntax are not correct.