Well... it'll probably take quite a bit of tweaking to make it look right, but, imo, you should start by loading the database items into a hidden listbox... or, forget the textbox and use a combo box that contains all items. Let the user type into the combo box instead.
Searching a database everytime the user presses a key will be slooowwww, at best.
If open to the 'hidden listbox' idea, here's code that'll quickly find text.
SendMessage: Quickly Find List Box Items using Full or Partial Matching
http://vbnet.mvps.org/code/listapi/findinglistitems.htmKeep in mind that the list will need to be searched on every single keypress and will need special handling for backspace, etc... including code to support the users ability to select a block and hit delete... and copy/paste, etc... this can be quite a chore to make it look right.... since the combo box has most of what you need built in, you might want to switch.