dropdown list box with datasource assigned in code but need to also manually add an item?

hello
I have some dropdown list boxes that I need to fill with data from a database but I also need the first option to be "Show All"... So I need to combine using a datasource and manually adding an item to the top of the list. I have tried two different ways with no luck:
1. with the appendDataboundItems = true, on aspx page, and below code in codebehind:

//lstClass.Items.Clear();                 //lstClass.Items.Add("Show All");                 lstClass.DataSource = ...