>We use Vfp3.0
>Since we don't want to write validation rules on the tables contained in the database.
>We prefer to validate the input on the valid method on the textbox.
>There is a 'Save' button on the form to update record. Can the Save button call all valid methods on the form?

if you're using the valid method in the textboxes, each field will be validated before you can move to another. the only thing you need to do is make sure that each field that MUST have an entry has been filled...