Calculated fields in a database

[Neil Winchurst]

I am learning knoda and hk-classes as a good way of setting up a
databases on Linux. I have used Linux for six years now and I have been
involved with databases for over 15 years. This knoda/mysql setup is
the best I have found so far in Linux.

I don't know about other people, but I find the help files rather
difficult to follow sometimes. For example there is no page explaining
how to set up a sub-form. I am still playing with that.

Calculated fields. Let me give an example of what I mean. You have a
list of people including date of birth. You need to have their age
showing on the form. Obviously this will change with time. So you need
a calculated field which takes the current date and subtracts the date
of birth to calculate the age. Since this is a calculated field it will
always be up to date and accurate.

The important thing about this 'age' field is that **it is not part of
any table. It appears on the form only.** There are other examples such
as a sales form which has a field to calculate the cost for each item
(price times quantity), and another field to show the total charge for
all the items. Again, these two fields will not appear in any table,
only on the form.

Is there any way in knoda/hk-classes to do this sort of thing? It is a
facility which I used again and again when I was writing databases in
Windows (using Borland Paradox).

Thanks for any help and/or information

Neil Winchurst