Re: Multi- Occurrence Data Structure

Larry Ducie wrote:

4. Re: Multi- Occurrence Data Structure (Larry Ducie)

<snip>
Yet we have no problem accepting the implicit "Cycle" that's a fundamental
aspect of SQL set-at-time processing.
</snip>

There is no implicit cycle in SQL. It may be there, but its not implied.

Larry:

I guess I have to ask for some instruction here. Say that I have a statement such as:

==> update myfile set x='1' where y='z'

Why is that not equivalent to a "cycle" (implicit DO-loop) such as (pseudo-code):

read myfile;
do while not EoF
if y='z'
x='1';
update myfile;
read myfile;
enddo;

I've never even considered that there was no implicit "cycle" inside of SQL's set operations. It was natural for me to see SQL in terms of a "cycle" since I'd used RPG for years before SQL started catching on. I've always thought the opposite, that cursor operations commonly involved more explicit cycle coding rather than the implicit "cycle".

Perhaps it's a terminology difference.

Tom Liotta