Re: The Practical Benefits of the Relational Model

"Paul" <pbrazier_at_cosmos-uk.co.uk> wrote in message news:51d64140.0210290216.7a8d3b97_at_posting.google.com...
> paul_geoffrey_brown_at_yahoo.com (Paul G. Brown) wrote in message
news:<57da7b56.0210281709.262a4094_at_posting.google.com>...
> > Call it what you will, but the concept of a 'user-specified unit of
> > work' seems to me to be a necessary feature of any data language. At
points
> > within a multi-query operation the database can be inconsistent, but not
> > at the end.
>
> Isn't this just a question of syntax?

No.

> Suppose our query language could only insert one value into one column
> and one row at a time. Then to insert a whole row we would need one
> statement for each column, all contained in a transaction. But instead
> we have a relational operator with this transaction "built-in".

You should think in terms of varables and values. It will help you think more cleary (well it helps me - as far as I can tell ;-)

The only operations in a relational database are

Assign a value to a variable
Assign a tuple value to a tuple variable Assign a relation value to a relation variable Assign a database value to a database variable

Things like INSERT a row, or UPDATE a column etc are just shorthands for one of the above.

Regards
Paul Vernon
Business Intelligence, IBM Global Services Received on Sat Nov 02 2002 - 19:36:20 CET