Re: List Box from Combo Box
There's no need to handle any events at all. Proper data binding will handle all the control updating for you. I'm not going to say more until you specify which version you're using because the details will be different for each. There are radio buttons provided when you create a thread. Please use them.
Re: List Box from Combo Box
Is your listbox databound or are you manually populating it in a loop?
You would need to, rebind a new datasource or repopulate in the loop, passing the new sql query with the combo box selection as part of the where clause to filter the results as your user selected
Re: List Box from Combo Box
In the SelectedIndexChanged event of the ComboBox, you need to connect to the database and query for data that match whatever the combobox's selected item means.
Once you have the data, just bind it to to the listbox.