Author: Tomas Rutkauskas 

Allow Incremental Searching in your TDataSets

Answer:

If you implement your search box (against a TDataSet) with a regular Locate() or 
FindKey() call requires that the user has typed in the exact search expression. It 
is much more handy to jump to the first match based on a partial search. E.g. if 
your user searches for the month 'August' in the list of 12 months' names, the user 
would type in 'A' and the cursor would jump to 'April'. Then the user would type 
the second letter.. 'u' and 'August' would be selected. This is called 'Incremental 
Searching'.

The following piece of code shows how to do it - put it as the onChange event 
handler of your form's edit box.
1   
2   procedure TForm1.Edit1Change(Sender: TObject);
3   begin
4     // empty? then do nothing!
5     if Edit1.Text = '' then
6       exit;
7   
8     //goto nearest match
9     with Table1 do
10    begin
11      SetKey;
12      FieldByName('Month').AsString := Edit1.Text;
13      GotoNearest;
14    end;
15  end;