Update Database column between two dates

Hi Everybody

I'm a beginner in scripting and attempted to find the answer in the form but might not have had the vocabulary to getting about finding what I wanted.

I am working with a waiting list for clients such that I need to update the whole database of how many days people have been waiting.

An initial date has been entered when a request was made, but unless I enter in each file manually and save the database will not update how many days the client is waiting.

I am use this script when I enter the form (Onshow) and when I click the Save button to update the table.

VAR
    // Calculate number of days client on waiting list.
    i : integer;
    iDays: integer;
    start, stop: integer;

Begin    // Calculate the number of days client is on waiting list.
    if ClientCreate.DateAssigned.Checked = false  then
         begin
            iDays := 0;
            start := Trunc (ClientCreate.DateDiscipline.date);
            stop := Trunc (date);
                 for i := start to stop do
                         Inc(iDays);
                Begin
                      ClientCreate.ClientDaysWaiting.Value := iDays;         
                end;
         end;

I would like to have a script that upon entering the main menu, the table for all the clients is updated automatically.

Any help would be greatly appreicated.

Tks.
Jeff