It`s easy, do something like this: (it's pseudocode)
searchView.setOnQueryChangeListener(new OnQueryChangeListener() {
public void onQueryChanged(String query) {
Cursor suggestions = dbHelper.getSuggestionsByQuery(query);
//dbHelper is object that handles interactions with your DB
SimpleCursorAdapter suggestionsAdapter = new SimpleCursorAdapter ... ;
searchView.setSuggestionsAdapter(suggestionsAdapter);
}
});