Updateable recordsets

[Reinhard Müller <reinhard mueller bitsmart com>]

I have taken a look at the possibility to make
recordsets updateable. Unfortunately, I have
found some issues that really could get us
in the way:

With client-side cursor (only possibility that
is currently implemented) the gda-server does
not know which is the current record and thus
can't update/delete it. Probably, the update
of recordsets would have to be implemented
client-sided (,too).

Apart from that, we will run into problems
when we have joins. Consider the statement

select name, country_id, text from customer,
country where customer.country_id = country.id;

We can't find out if text is a field of the
customer table or of the country table,
except we analyze the database schema.

When field values are allowed to be changeable
(which must be to make recordsets updateable),
a change of the value of the field "country_id"
would have to result in re-reading the country
table to obtain the new value for country.text.

All that means very much that GDA will have
to deal with how the tables of the database
are related to each other.
Of course that would be possible to do by
analyzing the SQL select statements and
the table schemes, but at a high effort.
On the other hand, there will in every case
sit an application on top of GDA that already
knows about all these relationships.
Exactly that application that generates the
SQL select statement could with not very
much additional effort create like SQL insert,
delete and update statements.

Not that I want to get out of it :) but I really
have to ask this question again:

Do we really want updateable recordsets in gda?

Thanks,
--
Reinhard Müller
GNU Enterprise
reinhard@gnue.org
http://www.gnue.org