There are a couple of 3rd party tools that will generate code to update a database based on changes you have made to it. You should look into the Stonefield Database Toolkit and xCase. Both of these tools also have a lot of other features you might find worthwhile.

I usually just keep a prg around to make all the changes. Any time I need to make a change to the db structure I just code it in my upgrade prg and run it. I make sure it won't blow up if the change has already been made, so I can always run it at the client site and get them to the latest version. For example, if I wanted to add a new field called MyField, I would do this:

USE mytable EXCLUSIVE
IF FSIZE('MyField')=0  && The field doesn't exist
   ALTER TABLE MyTable ;
      ADD COLUMN MyField C(20)
ENDIF

>When updating existing application at client site with newer version, what is the best method for handling new fields in tables ?
>How about the DBC if the changed tables are part of it ?
>
>Thanks !!