Use Items to specify the values the user can choose from. Because Items is an object of type TStrings, you can add, delete, insert, and move items using the Add, Delete, Insert, Exchange, and Move methods of the TStrings object. For example, to add each string to the listbox, write code such as the following:

while not CountryTbl.Eof do begin
  DBListBox1.Items.Add(CountryTbl.FieldByName('Country').AsString);
  CountryTbl.Next;
end;

DBListBox1->Items->Add("AFieldValue");

ItemIndex 

Using TDBListBox and TDBComboBox